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Sustainable employability of ageing workersKoolhaas, Wendy

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Sustainable employability of ageing workers

The development of an intervention

Wendy Koolhaas

Colofon

This study was conducted within the Research Institute SHARE of the Graduate School of

Medical Sciences, University Medical Center Groningen, University of Groningen and

under auspices of the research program Public Health Research (PHR).

The printing of this thesis was financially supported by the Graduate School of Medical

Sciences, Research Institute SHARE, University Medical Center Groningen, and the

University of Groningen.

Title Sustainable employability of ageing workers. The development of an

intervention. – with summary in Dutch

Cover design Bert Cornelius en Wendy Koolhaas

Foto Monique van den Berg; wandelaar Robbert de Bruin

Printed by Gildeprint, Enschede

ISBN 978‐90‐367‐6722‐4

© 2014 Wendy Koolhaas, The Netherlands

All rights reserved. No part of this thesis may be reproduced or transmitted, in any form or

by any means, without permission of the author.

Sustainable employability of ageing workers


Proefschrift

ter verkrijging van de graad van doctor aan de Rijksuniversiteit Groningen

op gezag van de rector magnificus, prof. dr. E. Sterken

en volgens besluit van het College voor Promoties.

De openbare verdediging zal plaatsvinden op woensdag 22 januari 2014 om 11.00 uur

door

Wendy Koolhaas geboren op 5 januari 1980 in de Noordoostpolder

Promotores Prof. dr. J.J.L. van der Klink Prof. dr. J.W. Groothoff Copromotor Dr. S. Brouwer Beoordelingscommissie Prof. dr. ir. A. Burdorf Prof. dr. F.J.H. van Dijk Prof. dr. M.F. Reneman

Paranimfen: Cindy Koolhaas Rudy Koolhaas

Contents

Chapter 1 General introduction

9

Chapter 2 In‐depth study of the workers’ perspectives to enhance sustainable working life: comparison between workers with and without a chronic health condition J Occup Rehabil. 2013;23(2):170‐9

19

Chapter 3 Toward a sustainable healthy working life: associations between chronological age, functional age and work outcomes Eur J Public Health. 2012;22(3):424‐9.

43

Chapter 4 Chronic health conditions and work ability in the ageing workforce: the impact of work conditions, psychosocial factors and perceived health. Int Arch Occup Environ Health. 2013 May 16. [Epub ahead of print]

61

Chapter 5 Coping, job control and social support as adaptation determinants of work ability among ageing workers with and without a chronic health condition. Submitted for publication

85

Chapter 6 Enhancing a sustainable healthy working life: design of a clustered randomized controlled trial. BMC Public Health, 2010; 10; 461

105

Chapter 7 Effectiveness of a problem‐solving based intervention to improve sustainable employability of ageing workers. Submitted for publication

127

Chapter 8 General discussion

153

Summary Samenvatting Research Institute for Health and Research (SHARE) and previous dissertations Dankwoord Curriculum vitae

171 179 189 195 201

Voor Eddy en Kim Eelde, december 2013

1

General introduction


11

AGEING OF A WORKING POPULATION

The ageing population is an important topic in political, societal and economic debates,

especially regarding the working population1‐3. Ageing is not simply an effect of time, but

refers to changes in biological, psychosocial and social functioning over time, and

therefore has an effect on a personal, organizational and societal level4‐8. To offset some

of the pressure that an ageing population will place on the economy, it is important to

increase the labour market participation of older workers9.

In the Netherlands, as in most welfare states, the impact of an ageing population is being

felt and is changing the face of the country10. The relative demographic decline has been

driven by a sharp fall in fertility rates and increased life expectancy3,11. The average

fertility rate declined from 2.5 in 1970 to 1.6 in 1980 and was stable for the last decades

around 1.7 children per female (Central Bureau of Statistics 2013). In addition, life

expectancy has increased from 72.5 years for males and 79.2 years for females in 1980 to

79.1 and 82.8 years, respectively, in 2012, and is expected to rise above 85 years by 2050

(Central Bureau of Statistics 2013)12. Moreover, the life expectancy of older people has

increased particularly rapidly. While men and woman who are currently 65 can now

expect to live for another 17.9 and 20.8 years respectively, this is forecast to increase to

20.7 and 23.5 years respectively by 2050 (Central Bureau of Statistics 2013). This means

that employers no longer have access to a steady supply of young, educated workers and

will need to rely more than before on older workers to remain competitive in the global

marketplace in the future.

Since 2006, the Netherlands has successively introduced a number of financial

instruments to encourage older workers to continue working and employers to hire them

and retain them in employment13. For example, an important aspect is increasing the

retirement age determined by the public pension system from 65 to 67 years of age; the

statutory retirement age will rise by one month per year from 2013 onwards till in 2025

the pension age is set at 67. The factual age at which people retire have risen from 61.0

years of age on average in 2000 to 63.6 years in 2012. Moreover, while 30% of workers

who retired in 2011 were 65 or older, this percentage increased to 42% in 2012 (Central

Bureau of Statistics 2013). By 2025, the retirement age will have increased to 67 and

might rise further as life expectancy increases13.

While until recently an early exit from the labour market was supported in the cases of

workers with age‐related problems such as a chronic health condition or a physically

demanding job, such workers now have to continue working despite their vulnerability in

Chapter 1

12

the labour market and their weakened capacity. From literature it is known that especially

after the age of 45, a variety of factors can diminish a worker’s quality of life, such as an

age‐related decline in health which can negatively affect various cognitive processes (i.e.

memory recall, speed and sensory functions) and musculoskeletal capacity (i.e. poorer

muscular strength, endurance and flexibility)14‐17. The ageing process is also associated

with increased absences due to sickness18 and the discontinuation of working life19‐21. To

enable workers to continue work participation and increase their sustainable

employability, it is important to maintain and promote their health and vitality.

Knowledge about the determinants as well as the perspectives of ageing workers

concerning continuing work until retirement age is required; at the one hand to

understand how they might overcome workplace challenges and at the other hand to

develop interventions to enhance sustainable employability.

CHRONIC HEALTH CONDITIONS

Chronic health conditions typically begin in middle age7,22,23 and have an adverse impact

on the employability of workers24‐26. An increase in chronic health conditions has been

recognized as a feature of the demographic and epidemiological transitions in our

population over the last century22,23,27.

In the Netherlands, 37% of workers reported a chronic health condition and about 20% of

those workers were hampered in the performance of their work28,29. Given the fact that

the prevalence of chronic health conditions generally increases with age, and that workers

will be required to work until they are older due to the ageing population, the prevalence

of chronic health conditions in the work place can be expected to increase even further in

the coming decades7,30. In 2011, it was expected that male workers of 45 years of age will

live for another 36 years, of which 12 will be without a chronic health condition, while

female workers of 45 years of age can expect to live for another 39 years, of which 13 will

be free of chronic health conditions. This implies that in the last ten years of their working

life half of the workers have to deal with a chronic health condition.

Multimorbidity, defined as ‘the co‐occurrence of multiple chronic conditions or acute

disease and medical conditions within one person31 is also a growing concern. Previous

studies have shown that workers with a chronic health condition, depending upon the

condition, experienced difficulties in meeting the physical and psychosocial demands of

their job32. To gear work demands and activities to the personal capabilities of a worker to

ensure they remain employable in the coming decades requires a strategy for workers

with a chronic health condition. This strategy should assist them to solve problems


13

associated with their working life, giving them the confidence in their ability to effectively

carry out actions which ensure their sustainable employability33,34.

INCREASING SUSTAINABLE EMPLOYABILITY OF AGEING WORKERS

The changing situation of the workforce as outlined above endorse the necessity of

attention to sustainable employability on macro‐ (e.g. pension adequacy and income

maintenance), meso‐ (e.g. personnel policy which provide resources for career

perspectives), and micro level (e.g. the workers’ health). The challenge is to keep the

relatively large group of ageing workers motivated and employable, and this should be

accomplished without threatening the wellbeing. To keep workers in the labour market

during the coming decades, employers should invest in the implementation of policies,

education on the job and working methods to enable workers to have the necessary

competencies for longer working lives2,35.

During last decades, the nature of work has changed due to globalization and information

technologies and work‐based life‐long learning is required to maintain and enhance

employable36. Moreover, the more dynamic market and shorter product cycles have

resulted in fewer jobs, with frequent job changes over a working lifetime. Due to these

changes in the labour market, the worker‐employer relationship has evolved from one of

mutual loyalty to one based on mutual gain, but with personal responsibility of the

worker. Workers are increasingly responsible for their own career, and they need to be

aware of their own responsibility and decisive role in creating and/or maintaining a

healthy work life. To encourage workers to control their own employability until

retirement, the development of an intervention is necessary which offers a strategy to

identify problem, challenges, and solutions to increase the workers’ problem solving

capacity towards sustainable employability.

Up until now, most intervention studies to promote workers’ health to extend working life

provide workplace interventions for specific group of workers, to improve job retention 37,

increase vitality38 or decrease work disability and sickness absenteeism39‐42. However, to

gear the work demands and activities to the personal capacities of the ageing worker, a

strategy to solve problems with regard to ageing and chronic health conditions is required.

As a preparatory step toward developing such an intervention, the specific characteristics

of the target group need to be assessed. More specifically, the needs and determinants of

the target population should be gathered43. Next important steps are the development

and evaluation of the intervention.

Chapter 1

14

OBJECTIVES OF THIS THESIS

The objectives of this thesis are:

1. To provide insight into the needs and determinants regarding a sustainable

working life among workers aged 45 years and older, with and without chronic

health conditions;

2. To develop and evaluate an intervention aimed at enhancing sustainable

employability.

Based on a literature study1,44‐46, ageing workers in this thesis are defined as ‘workers aged

45 years and older’. The presence of a chronic health condition is defined as ‘the

subjective experience of a long‐term irreversible disease of more than 3 months duration’,

which is in accordance with the definition used in many other studies47,48.

OUTLINE

Chapter 2 describes the workers’ perspectives on the problems experienced due to

ageing, obstacles to performing work tasks due to ageing, retention factors that ensure

work participation, and support needs required to continue working in the coming years

for workers with and without a chronic health condition. The type and number of

problems experienced, the obstacles, the retention factors and the needs are presented.

An in‐depth research approach was chosen as it offers a deeper understanding of

perceived motives and factors associated with maintaining work participation. In

Chapter 3, the relationship between chronological and functional age is determined, and

the association between chronological age and functional age and five work outcomes is

examined: work ability, problems, obstacles, retention factors and needs due to ageing. In

Chapter 4, the influence of work conditions, psychosocial determinants and perceived

health is determined in relation to the association between a chronic health condition and

work ability. Variables associated with work ability are examined separately for workers

with and without a chronic health condition. Chapter 5 focuses on the association

between different coping strategies and work ability and the modifying effect of job

control and emotional and instrumental support for ageing workers. In addition,

differences between workers with and without a chronic health condition are determined.

Chapter 6 describes the study design of the intervention ‘Staying Healthy at Work’.

Chapter 7 presents the effectiveness and process evaluation of the intervention ‘Staying

Healthy at Work’, and Chapter 8 provides a general discussion. The main findings of this

thesis are summarized and discussed, methodological considerations are addressed and

the recommendations for future use of the intervention, and for policy and practice are

presented.


15

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workplace to reduce the risk of cardiovascular disease ‐ a systematic review. Scand J Work Environ Health

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based health education programs. Health Educ Behav 1998;25:545‐563.

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workers' lifestyle and vitality‐related outcomes: results of a randomised controlled trial. J Epidemiol

Community Health 2012;66:1071‐1078.

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diseases. Int J Occup Saf Ergon 2006;12:17‐30.

46. Ageing at work: consequences for industry and individual. Lancet 1993;341:87‐88.

47. Beatty JE, Joffe R. An overlooked dimension of diversity: The career effects of chronic illness. Organ Dyn

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48. De Klerk MMY. Rapportage gehandicapten 2000: arbeidsmarkt en financiële situatie van mensen met

beperkingen en/of chronische ziekten [Report of the handicapped 2000: employment and financial

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2000.

2

In‐depth study of the workers’ perspectives to enhance

sustainable working life: comparison between workers with

and without a chronic health condition

J Occup Rehabil. 2013 Jun;23(2):170‐9

W. Koolhaas

J.J. van der Klink

J.P. Vervoort

M.R. de Boer

S. Brouwer

J.W. Groothoff

Chapter 2

20

ABSTRACT

Purpose: To gain in‐depth understanding of the number and type of experienced ageing

problems, obstacles to perform work tasks, retention factors to maintain work and

support needs to continue working life in the next years among workers aged 45 years and

older with and without a chronic health condition.

Methods: A survey of workers’ perspectives on problems, obstacles, retention factors and

needs due to ageing was carried out in 3008 workers aged 45 years and older in nine

different companies. To classify the open‐ended questions we used the International

Classification of Functioning and disability (ICF).

Results: Older workers with a chronic health condition reported more problems due to

ageing (56% vs 34%; p<.001), more obstacles (42% vs 16%; p<.001) and more needs (51%

vs 31%; p<.001) compared to those without a chronic health condition. No relevant

differences were found on type of experienced problems, obstacles, retention factors and

needs between both groups. Problems and obstacles were found on physiological and

psychological functions. Retention factors and needs to enhance sustainable working life

were particularly reported on work‐related environmental factors.

Conclusion: Because workers with a chronic health condition experienced more problems,

obstacles and needs, the largest gain of occupational intervention can be achieved in

these workers. However, our findings suggest that interventions aimed to enhance

sustainable working life of older workers can be similar in content for persons with and

without chronic health conditions and should have a central focus on work‐related factors.

Keywords: Ageing problems, Chronic health condition, Obstacles and retention factors,

Support needs, Sustainable working life, Workers’ perspectives

Workers’ perspectives to enhance sustainable employability

21

INTRODUCTION

Because of the ageing population, employers will be confronted with manpower in which

older workers are represented more strongly than before1. Enabling and encouraging

older workers to remain on the labour market is important. Mobilising the full potential of

older people is a key response to those demographic changes, which require the

promotion of a healthy working life2. However, the process of ageing burdens on physical

and mental health status3 and is significantly associated with a decreased work ability4 and

early discontinuation of working life5,6. Due to the aging population, an increase of the

incidence of chronic health conditions in the working population is expected in the next

twenty years. Perceived health declines with age, and the prevalence of chronic health

conditions increases after the age of 45 years7,8 and have an adverse impact on the

employability of the older workers9,10. The higher prevalence of chronic health conditions

is in turn strongly related to more ‘fatigue’ and ‘emotional exhaustion’, which are

correlated with perceived work stress11,12. Thus, deterioration in health status due to

ageing will make workers more vulnerable in the labour process.

The increase in problems due to ageing as well as health related problems from the age of

45 years onwards implies the importance of attention to obstacles and retention factors

for maintaining or enhancing a sustainable working life. Several prognostic studies have

identified problems and risk factors associated with sustainable employability for ageing

workers in general13‐16. However, little is known about the workers’ perspectives on

obstacles, retention factors and support needs with regard to continuing their working

life. There have been some studies on obstacles and motivators in the work situation from

a patients’ perspective or workers with health conditions, but these have been conducted

in specific populations12,17,18. In addition, several studies have shown that the presence of

a chronic condition has impact on work ability3,19, work disability8 and productivity9.

Therefore it is conceivable that the number and type of problems, obstacles, retention

factors and needs differ between workers with and without a chronic health condition.

Insight into these factors is an important next step towards the development of strategies

and (preventive) measures aimed at addressing the potential workforce shortages in daily

practice.

The aim of the present study is to compare the number and type of experienced

problems, obstacles, retention factors and support needs among workers aged 45 years

and older with and without a chronic health condition.

Chapter 2

22

METHODS

The data of this cross‐sectional in‐depth survey study were obtained from workers aged

45 years and older. Nine companies in the northern part of the Netherlands, invited by

their occupational health physicians, were willing to participate in the study. Three large

size companies (≥1000 workers), two medium sized companies (≥500 workers) and four

small companies (<500 workers) participated. These companies represented four sectors:

health care (two companies; n=4097), education (3 companies; n=3167), government (1

company; n=563) and industry (3 companies; n=590). A self‐administrated questionnaire

including an information letter about the study with instructions on how to fill in the

questionnaire was send to all workers aged 45 years and older of the nine companies (n =

8417). All companies enclosed a letter of recommendation. The anonymity of respondents

and confidentiality of the information they provided were guaranteed. Four weeks after

the initial mailing, all workers received a written reminder. The data were collected in

February and March 2008.

Ethical approval was sought from the Medical Ethics Committee of the University Medical

Center Groningen, which advised that, according to Dutch law, ethical clearance was not

required for this study.

Measures

We used self‐constructed dichotomous (yes/no) questions and open‐ended questions. The

first question assessed whether the workers experienced ageing problems: ‘Do you

encounter problems in working life due to ageing?’. The next two questions concerned the

obstacles and retention factors for continuing working life: ‘Do you experience obstacles

in performing work tasks due to ageing problems?’ and ‘Are there factors in your work

which facilitate you in maintaining a sustainable working life?’. The fourth question was

about the support needs to continue working life in the coming years: ‘Do you need

support in the work situation to continue working life in the coming years despite

ageing?’. For each question with a ‘yes’ answer, the workers were asked to report a

maximum of the three most important examples which were on top of their mind.

Additionally, the questionnaire included questions about: age, gender, education,

occupation, sector and whether the worker experienced a chronic health condition.

Education was categorized into no education/primary school, lower vocational education,

intermediate secondary and vocational education, higher vocational education and

university and other or unknown. Occupation was divided into four groups: executive,

secretarial, policy and management. In accordance with many other studies, a chronic

health condition was defined as ‘the subjective experience of long‐term irreversible


23

disease of more than 3 months duration’20,21. It was assessed by asking the respondents

the following question: ‘Do you currently have a long‐term or chronic health condition of

more than 3 months duration without the prospect of recovery?’(yes/no).

Classification system

To classify and compare the workers’ perspectives we used the International Classification

of Functioning, Disability and Health (ICF)22. The ICF is a classification of human functioning

and disability developed by the World Health Organisation to systematically categorize

health and health‐related states as well as contextual factors that may impact those

states22. It offers a taxonomy for the classification of functions, structures, activities,

participation and a list of external factors. The ICF does not contain a taxonomy for work‐

related external factors and no consensus has been reached for a list of personal

factors23,24. Therefore, we used the expanded classification as described by Heerkens et al.

to classify the work‐related external factors23. For the personal factors we used the update

of the provisional list of personal factors as described in the Newsletter on the WHO

Family of International Classifications24.

Classifying data

To link the data to the ICF codes, the updated linking rules developed by Cieza et al. were

used25,26. Following the linking rules, the open ended data was linked to the most

appropriate corresponding ICF category, identified with its unique alphanumeric codes

that indicate the components of the ICF: ‘Body functions’ (B), ’Body structures’ (S),

‘Activities and participation’ (D), ’Environmental factors’ (E). For classifying the ‘Work‐

related environmental factor’ and ’Personal factors’ we used the alphanumeric codes ‘W’

and ‘P’ respectively. In each classified component of the ICF, the categories are arranged

in a stem‐branch‐leaf scheme. Consequently, a higher level (more detailed) category

shares the lower‐level categories of which it is member. Classification of the data in this

study took place on the highest level available of the ICF components (mostly fourth or

fifth). If the example reported by the workers did not provide sufficient information to

make a decision about the most precise ICF category, the concept was deemed not

definable and was assigned the code Nd (Not defined). When not definable answers

referred to a health condition we used Nd‐hc (Not defined‐health condition). If an answer

described an aspect, which was not covered by the expanded ICF, it was assigned Nc (Not

covered)25.

We conducted a pilot to test the usability of the ICF in the current study. Two practising

occupational health physicians, all familiar with the ICF, and the first author (WK)

Chapter 2

24

categorised a random sample of 200 workers independently, and compared and discussed

their results. In case of disagreement (16%), differences were discussed until consensus

was reached. During the pilot we developed a short list of the relevant ICF‐codes in our

study. During the pilot we developed a short list of the relevant ICF‐codes in our study. In

addition, the usability of the additional stem‐branch‐leaf scheme for the ‘Work‐related

environmental factors’ and ’Personal factors’ was tested. An short example of the list of

classification codes used in this study is shown in Table 1. The complete list used in this

study can be obtained from the authors. Two authors (WK, JV) categorised all data. They

categorised 30% independently and compared their results, to minimize the risk of bias.

Data analyses

A description of the socio‐demographic characteristics was given by frequencies, standard

deviations, means and percentages for the total sample and for both groups of workers

with and without chronic health conditions. To estimate differences between both groups

the t‐test was used for the continue variable age. The chi‐square statistics was used for

the categorical variables. We examined the differences in proportion of persons

experiencing problems, obstacles, retention factors and needs between workers with and

without a chronic health condition by using logistic regression. We adjusted the analysis

for gender and occupation.

The number and type of problems due to ageing, obstacles, retention factors and needs to

continue work and the ICF codes identified were given by frequencies and percentages for

workers with and without chronic health conditions separately. The different problem,

obstacle, retention and need items were summated over the respondents and the top 10

most frequently reported were presented. All analyses were carried out with the

statistical package SPSS version 20.0 (IBM Corp. Released 2011. IBM SPSS statistics.

Armonk, NY).


25

Table 1: Example of the list of classification codes between the self‐reported answers and corresponding ICF components including the work‐related external factors and personal factors

ICF codea ICF category title

1st level 2nd level 3rd level 4th level

B1 MENTAL FUNCTIONS

B140 Attention functions

B1400 Sustaining attention

B144 Memory functions

B1441 Long‐term memory

B2 SENSORY FUNCTIONS AND PAIN

B210 Seeing functions

B2100 Visual acuity functions

B280 Sensation of pain

B2801 Pain in body part

B28010 Pain in head and neck

B28013 Pain in back

D4 MOBILITY

D415 Maintaining a body position

D4152 Maintaining a kneeling position

D4153 Maintaining a sitting position

D4154 Maintaining a standing position

D7 INTERPERSONAL INTERACTIONS AND

RELATIONSHIPS

D740 Formal relationships

D7400 Relating with persons in authority

D7401 Relating with subordinates

D7402 Relating with equals

E2 NATURAL ENVIRONMENT AND HUMAN‐MADE

CHANGES TO ENVIRONMENT

E225 Climate

E2250 Temperature

E2251 Humidity

P PERSONEL RELATED ENVIRONMENTAL

FACTORS

P100 Socio‐demographic factors

P1010 Age

P1020 Gender

P1030 Education

P1040 Partnership/marriage

Chapter 2

26

Table 1: continued

ICF codea ICF category title

1st level 2nd level 1st level 2nd level

P1050 Income

P500 Work related personal

P5010 Occupation/profession

P5020 Occupational status

P5030 Commitment to work

P5060 Work history

P5110 Need for work

P5120 Success

W WORK‐RELATED ENVIRONMENTAL FACTORS

W100 Work content

W1010 Job tasks

W10101 Supervising colleagues

W10102 Delegating tasks

W10103 Tasks reduction

W1020 Skills required

W1030 Decision authority

W500 Organisation

W5010 Organisation culture

W50101 Manners

W50102 General attitude towards absenteeism

W5010 Company type

a The complete list used in this study can be obtained from the authors


27

RESULTS

Out of the 8417 workers aged 45 and older who were invited to participate in the study,

3008 returned the self‐administered questionnaire. The mean response rate was 36% and

varied for the nine companies between 28% in a large health care company and 58% in

one small company in the industrial sector. We excluded 25 workers from the study

because of missing data on experienced problems, obstacles, retention factors or needs. A

description of the socio‐demographic characteristics is presented in Table 2. The mean age

of the workers was 53.4 years (SD 5.0) ranging from 45 to 64 years. Fifty‐one per cent of

the workers was female, and 60% was working in an executive occupation. Most workers

were highly educated (59%) and most of them were working in the sectors education

(42%) and health care (41%). Thirty‐seven per cent (n=1109) of the workers reported the

presence of a chronic health condition. Significant differences for workers with and

without a chronic health condition were found on gender and occupation. The percentage

of female workers was higher in workers with a chronic health condition. Workers in

executive (40%) and secretarial/administrative (41%) functions reported more chronic

health conditions than policy workers (32%) and management (29%).

Comparison of the experienced problems, obstacles, retention factors and support

needs

In the total sample, 1246 (42%) of the workers reported problems due to ageing, 763

(26%) reported obstacles to perform work due to ageing problems, 2451 (82%)

experienced retention factors maintaining a sustainable working life and 1142 (38%)

reported that they had special support needs to continue their working life in the coming

years (data not shown). Workers with a chronic health condition reported significantly

more problems due to ageing (56% vs 34%; p<.0001), more obstacles to perform work due

to ageing problems (42% vs 16%; p<.0001) and more support needs to continue their

working life in the next coming years (51% vs 31%; p<.0001) compared to workers without

a chronic health condition. The mean number of problems, obstacles and needs reported

per person were higher for workers with a chronic health condition compared to workers

without a chronic health condition, i.e. problems due to ageing (1.88 vs 1.74), obstacles

(1.93 vs 1.62) and support needs (1.51 vs 1.41). No difference was found between both

groups for the experienced retention factors (see Table 3).

28

Table 2: C

haracteristics and number of experienced problems, obstacles, reten

tion factors and needs

Total sam

ple

(n=2983)

Workers with a chronic health

condition (n=1109; 37%)

Workers without a chronic

health condition (n=1874)

n=2983

n

%

n

%

n

%

Mean age (SD

)

53.4 (5.0)

53.5 (4.8)

53.3 (5.0)

Female workers a

1527

51

621

56

906

48

Education

No education/ Primary school

52

2

21

2

31

2

Lower vocational education

451

15

181

16

270

14

Interm

ediate secundary and vocational education

707

24

264

24

443

24

Higher vocational education and university

1761

59

638

58

1123

60

Other or unknown

12

<1

5

<1

7

<1

Sector

Health care

1213

41

466

42

747

40

Education

1267

42

469

42

798

43

Production

231

8

98

9

174

9

Governmen

t 272

9

76

7

155

8

Occupationa

Executive

1786

60

708

64

1078

58

Secretarial / Administrative

375

13

152

14

223

12

Policy

385

13

123

11

262

14

Managem

ent

398

13

115

10

283

15

Unkown

39

1

11

1

28

1

a Chi‐square statistics shows significant differences between workers with and without a chronic health condition (p<.001)

29

Table 3: The number and type of reported

examples of the workers’ perspectives of problems, obstacles, reten

tion

factors and needs linked to ICF codes for workers with a chronic health condition

Workers with a chronic health condition (n=1109)a

Problems

Obstacles

Retention

factors

Needs

Number of workers who reported yes (%

)617 (56)

465 (42)

910 (82)

560 (51)

Mean (SD

) number of reported

per worker (Total

reported

/N (yes))

1.88 (0.82)

1.93 (0.83)

2.00 (0.84)

1.51 (0.74)

Reported answ

ers on the IC

F components

b

B Body functions

834

71

284

32

6<1

7<1

S Body structure

0‐

0‐

0‐

0‐

D Activities and Participation

80

7

262

29

449

24

37

4

E Environmen

tal factors

6<1

0

‐4

<13

<1

P Personal factors

6<1

9

<1302

16

16

2

W W

ork‐related

factor

177

15

331

37

1078

58

776

92

Not definable‐Health conditions

54

5

6<1

0‐

0‐

Not definable

6<1

4

<18

<15

<1

30

Table 3: continued

(for workers without a chronic health condition)

Workers without achronic health condition (n=1874)a

Problems

Obstacles

Retention

factors

Needs

Number of workers who reported yes (%

)629 (34)

298 (16)

1541 (82)

582 (31)

Mean (SD

) number of reported

per worker (Total

reported

/N (yes))

1.74 (0.80)

1.62 (0.79)

2.00 (0.83)

1.41 (0.69)

Reported answ

ers on the IC

F components

b

B Body functions

813

74

191

39

14

<11

<1

S Body structure

0‐

0‐

0‐

0‐

D Activities and Participation

66

6

92

19

752

24

26

3

E Environmen

tal factors

4<1

0

‐6

<12

<1

P Personal factors

13

1

0‐

467

15

6<1

W W

ork‐related

factor

186

17

196

40

1879

60

780

95

Not definable‐Health conditions

4<1

2

<10

‐0

‐

Not definable

2<1

3

<111

<17

<1a Logistic regression analyses, adjusted

for gender and occupation, shows significant differences betw

een experien

ced

problems due to ageing (p<.001), obstacles to perform

work (p<.001), and support needs continue their working life in

the next

coming years (p<.001) between workers with and without a chronic health condition

b W

orkers were asked

to rep

ort a m

axim

um of the three most im

portant exam

ples of these factors which were on top of their mind


31

Classification of the workers’ perspectives

After linking the data to the components of the ICF (Body functions, Body structures,

Activities and Participation, Environmental factors) the percentages of reported answers

on the ICF components showed similar results for workers with and without a chronic

health condition (CHC) (Table 3). The most experienced problems due to ageing were

reported on the ICF component ‘Body functions’ (with CHC: 71% vs without CHC: 74%),

followed by work‐related factors (15% vs 17%) and ‘Activities and Participation’ (7% vs

6%). Problems on the other ICF components were hardly reported. The most experienced

obstacles to perform work were reported least often on the ICF components ‘Work‐

related environmental’ (with CHC: 37% vs without CHC: 40%), ‘Body functions’ (32% vs

39%) and ‘Activities and Participation’ (29% vs 19%). The components ‘Work‐related

environmental’ (with CHC: 58% vs without CHC: 60%), ‘Activities and Participation’ (24% of

both groups), and ‘Personal factors’ (16% vs 15%) were reported as retention factors to

maintain a sustainable working life. Support needs to continue working life were

particularly reported on the component ‘Work‐related environmental factors’ with 92%

and 95% respectively for both workers with and without a chronic health condition.

The most frequently reported problems, obstacles, retention factors and needs were

similar for workers with and without a chronic health condition (see Table 4). Most

frequently experienced problems due to ageing were problems with energy level, recalling

information stored in long‐term memory and bringing it into awareness (retrieval of

memory), functions related to sustaining muscle contraction of all muscles of the body for

the required period of time (endurance of all muscles of the body) and the seeing function

for both distant and near vision (visual acuity functions). The most frequently reported

obstacles to perform work due to ageing problems were tasks which require

concentration for the period of time required (sustainable attention), lifting and carrying

object, working schedules and work pace. The most frequently reported retention factors

to maintain a sustainable working life were: creating and maintaining formal relations with

people in the same position (relating with equals), beginning and maintaining interactions

with others for a short or long period of time (forming relationships), job tasks and

creating and maintaining formal relations with people in positions of lower rank or

prestige relative to one's own social position (relating with subordinates). The most

frequently reported support needs to continue working life in the next coming years were

working less hours, tasks reduction, reducing time pressure, improvement of the physical

conditions in the work place and ergonomic adjustments (see Table 4).

32

Table 4: Top 10 of the most frequen

tly reported

type of ageing problems, obstacles, reten

tion factors and needs to continue

work of workers with and without a chronic health condition

Workers with a chronic health condition

Workers without a chronic health condition

ICF Code

Freq

%

Item

ICF Code

Freq

%

Item

Problems due to ageing

Total number reported n=1163


B1300

196

17

Energy level

B1300

207

19

Energy level

B7402

87

7

Endurance of all m

uscles of the body

B1442

100

9

Retrieval of mem

ory

B1442

76

7

Retrieval of mem

ory

B2100

72

7

Visual acuity functions

B7152

64

6Stability of joints generalized

B7402

70

6Endurance of all m

uscles of the body

B1400

53

5

Sustaining attention

B7800

40

4

Sensation of muscle stiffness

B2100

46

4


B1400

38

3


B7800

41

4Sensation of muscle stiffness

W1101

36

3Men

tal dem

ands –obtaining and

using new

knowledge

B28013

40

3

Pain in

back

B28013

33

3

Pain in

back

W1101

30

3Men

tal dem

ands ‐obtaining and using

new

knowledge

B7152

32

3Stability of joints generalized

B1643

24

2Cognitive flexibility

B6702

29

3Discomfort associated

with

men

opause

33

Table 4: continued

(obstacles)



ICF Code

Freq

%

Item

ICF Code

Freq

%

Item

Obstacles to perform

work due to ageing



B1400

134

15


B1400

89

18


D430

107

12

Lifting and carrying objects

W1080

45

9

Work pace

W3012

59

7

Working sched

ules

W3012

44

9

Working sched

ules

W1080

58

6

Work pace

D430

40

8

Lifting and carrying objects

W1010

57

6

Job tasks

W1010

24

5

Job tasks

B1300

37

4

Energy level

W3013

19

4

Shift work

W4011

24

3

Time pressure

B1300

13

3

Energy level

W3013

23

3

Shift work

B1442

13

3

Retrieval of mem

ory

W1101

22

2Men

tal dem


new

knowledge

W1200

12

2Men

tal dem


new

technologies

D4154

22

2

Maintaining a standing position

B2100

11

2


34

Table 4: continued

(retention factors)



ICF Code

Freq

%

Item

ICF Code

Freq

%

Item

Retention factors to m

aintain working life



D7402

322

17

Relating with equals

D7402

498

16

Relating with equals

D7200

157

9

Form

ing relationships

D7200

269

9

Form

ing relationships

W1010

139

8

Job tasks

W1010

217

7

Job tasks

D7401

131

7Relating with subordinates

W1101

196

6Men

tal dem


new

knowledge

P5050

117

6

Job satisfaction

D7401

198

6

Relating with subordinates

D7101

99

5

Appreciation in

relationships

D7101

168

5

Appreciation in

relationships

W1050

92

5

Autonomy

W2060

166

5

Work atm

osphere

W1101

82

4Men

tal dem


new

knowledge

P5050

165

5Job satisfaction

W2060

80

4

Work atm

osphere

W1050

150

5

Autonomy

P2060

72

4

Purpose in

life

W1060

115

4

Variation job tasks

35

Table 4: continued

(needs)



ICF Code

Freq

%

Item

ICF Code

Freq

%

Item

Needs of support to continue working life in

the next coming years



W1013

95

11

Tasks reduction

W3015

109

13

Working hours

W3015

87

10

Working hours

W1013

76

9

Tasks reduction

W4011

67

8

Time pressure

W4020

51

6

Physical conditions work

W4031

50

6

Ergonomic conditions ‐ furniture

W4011

50

6

Time pressure

W4020

48

6Physical conditions work

W4034

47

6Ergonomic conditions ‐tools and

machinery

W4034

39

5Ergonomic conditions ‐tools and

machinery

W3013

45

5Shift work

W5061

28

3

Policy of company

W4031

37

5

Ergonomic conditions ‐ furniture

W3013

24

3

Shift work

W3011

28

3

Working hours

W3012

20

2

Working sched

ules

W5010

24

3

Organisation culture

W4030

19

2

Ergonomic conditions

W5061

24

3

Policy of company

Chapter 2

36

DISCUSSION AND CONCLUSION

Our study shows that older workers with a chronic health condition experience more

problems due to ageing, more obstacles to perform work and more needs to continue

working life compared to older workers without chronic health conditions. Most problems

due to ageing were linked to the ICF component ‘Body functions’ (B) which covers

physiological functions of body systems, including psychological functions. Perceived

obstacles to perform work due to ageing problems were mainly related to the ICF

components ’Body functions’ (B), ’Activities and participation’ (D) and ’Work‐related

environmental factors’ (W). Retention factors for maintaining a sustainable working life

and support needs to continue working life in the next coming years, were particularly

reported on ‘Work‐related environmental factors’ (W). Relevant differences in type of

reported problems, obstacles, retention factors and needs with respect to enhance

sustainable working life between workers with and without chronic health conditions

were not found.

In the past few years several studies have demonstrated that health status has a

profound impact on the ability of workers to be actively engaged in paid employment and

to prolong their meaningful contribution to a productive society3,4,13. There is evidence

from longitudinal studies that poor health, in particular self‐perceived poor health, plays a

role in exit from paid employment27‐29. Our findings that workers with chronic conditions

experience more problems and obstacles and reported more support needs emphasize

the vulnerability of this specific group of older workers and their need for preventive

occupational interventions.

We found no large differences between workers with and without a chronic

health condition with respect to the type of experienced problems, obstacles, retention

factors and needs. Previous studies focussed on understanding why older workers

continue to work and the obstacles and retention factors they encounter are mostly based

on specific perspectives. These studies showed perceived perceptions of constraints of

older workers (>60 years)30‐32, the ability to carry on working in specific occupations13,16, or

working with (specific) chronic health conditions12,18,33,34. Differences between workers

with and without a chronic health condition we found in literature were addressed to

fatigue, emotional exhaustion and perceived health complaints11. Qualitative or in‐depth

studies from the workers’ perspectives of experienced types of ageing problems,

obstacles, retention factors and needs in working life to compare with our results are

scarce. Moreover, data about differences between workers with and without a chronic

health condition of relevant factors from the workers’ viewpoint to enhance sustainable

working life were not found. That we found no differences in types of problems, obstacles,


37

retention factors and needs between workers with and without a chronic health condition

might suggest that preventive occupational interventions do not need to differentiate

between workers with and without a chronic health condition.

The importance of the components ‘Body function’ and ‘Work‐related

environmental factors’ was in line with our expectations. Ageing has been found to be

strongly related to a decrease in physical and cognitive functioning3,35,36. Good health and

physical fitness were perceived to be facilitators to work participation from the workers’

point of view31,32. In addition, prognostic studies focussing on different working

populations or health conditions have shown that work related adjustments such as

reducing work hours, changing the type of work, reducing physical demands and work

stress were relevant factors to maintain work participation12,13,37. This study shows that

most workers are aware that their problems due to ageing mainly concern ‘Body

functions’. However, they assume that the burden of these ageing problems will not

disappear and that adjustments in the work situation are necessary to enhance

sustainable working life. In line with this they report work‐related retention factors and

needs to remain and continue work participation. With respect to preventive occupational

interventions this suggest that workers at risk could be identified by their problems on

‘Body functions’, but that the intervention must focus on creating a balance between

workload and the workers individual capacity.

As many problems, obstacles, retention factors and needs are named by the

participants in this study, the results do not indicate a specific intervention. Nor do the

results support the development of different interventions for workers with and without a

chronic health condition. Most experienced problems are reported on the ICF component

‘Body Function’, but the impact of those problems on obstacles to perform work were

different from the workers’ perspectives. Obstacles were reported on the ICF components

‘Body Functions’, ‘Activities and Participation’ as well as ‘Work related factors’. Support

needs to continue work were particularly reported on the ICF component ‘Work‐related

factors’. However, the requested adjustment were spread on different work‐related

factors. Thus, a preventive intervention to overcome the challenge of an ageing workforce

should be tailor‐made and able to deal with individually experienced problems and needs.

From previous research we know that empowerment and self‐management interventions

could contribute to a sustainable working life for both workers with and without a chronic

health condition38,39. It is also known that supervisors are most likely to receive the first

request for accommodations from workers and are responsible for facilitating these

workers40,41. Therefore, important elements of such a preventive and tailor‐made

intervention should base on: a) an inventory of (work‐related) problems, obstacles and

Chapter 2

38

personal development opportunities, and b) the possibility to discuss work‐related

environmental factors and adaptations based on the individual worker. A booklet for

workers to encourage a structured dialogue with the supervisor to identify the

experienced problems and to explore possible solutions of the worker, might be a useful

starting point for a tailor‐made and effective intervention in which both the worker and

the supervisor can take their responsibility. Such an intervention is focussed on increasing

the problem‐solving capacity of the workers and stimulating their awareness of their role

and responsibility towards a healthy working life, with support of the supervisor.

A strength of our study is that we used open ended questions to give as much

room as possible to the workers’ own perspective on their problems due to ageing,

obstacles and retention factors in work participation and needs to continue working life.

This design elucidates data from the experiences of the workers themselves, because the

questions were not directed towards a number of set answering categories. The open‐

ended questions enabled authentic themes to be named, independent from prevailing

constructs, instruments, or questionnaires, and thus give an in‐depth overview. However,

this study is not a qualitative study, but an in‐depth study of the workers’ perspectives on

problems, obstacles, retention factors and needs to increase sustainable work.

Subsequently, the data was categorised by using the framework of the ICF model. The ICF

proved highly useful for the content comparison of the workers’ perspectives of the open‐

ended data. Expanding the ICF classification by using a list of work‐related environmental

factors and personal factors as well was helpful. However, in a future revision of the ICF

component ‘Work‐related environmental factors’ the classification of job tasks could be

more specified (e.g. tasks reduction, supervising colleagues, teamwork) and aspects

referring to ‘working at home’ should be included.

A limitation of this study is that the overall response rate of 36% at baseline could

have led to selective participation. Because of the anonymous study design, we were not

able to investigate the characteristics of the non‐responders properly. The results of our

study might not be representative for workers in the production sector because of the

underrepresentation of these workers in our study. Nevertheless, we believe there is no

reason to expect that workers with problems due to functional age or a chronic health

condition returned the questionnaire less frequently than workers without problems. The

questionnaire addressed a variety of themes, and did not emphasize functional age or

chronic health conditions. Another potential limitation is that the current study does not

distinguish between specific chronic health conditions because of the lack of knowledge of

the severity and limitations of the conditions. It is possible that severely ill and chronically


39

disabled are in most cases excluded from working life and their perspectives are not

included in our sample. The workers who are still working, might be a select, relatively

healthy group of the general population of this age. Because of this selection bias due to

the healthy worker effect, the results in this report are probably an underestimation of

the problems in the entire age group42,43.To make no difference between workers

suffering from various chronic health conditions in relation to a sustainable working life is

supported by Detaille et al. among physically ill workers18,44. They showed that different

groups of chronically ill workers were experiencing the same themes that they perceived

to be important for continuing their work, although their priority varied. Finally, this study

is an in‐depth study using open ended questions, but it is not a qualitative study involving

material derived from interviews or observation. Defining and judging the open ended

data was sometimes difficult because the context for interpretation was missing.

However, to control for the quality of the information gathered, a two step‐method was

used. First, we conducted a pilot study. In a further attempt to minimize the risk of bias,

an additional 30% of the data were analysed independently by two authors. We assume

that the opportunity to gain in‐depth information of the workers’ perspectives of a large

group of workers in different occupations and organisations is more valuable than using

predefined constructs or a small set of qualitative data. Moreover, because of the

complementary knowledge of the investigators and the generally clear description of the

open‐ended answer, we do not expect that the method used in this study has led to a

distorted picture.

In conclusion, older workers with a chronic health condition reported significantly more

problems due to ageing as well as obstacles to continue their working life and support

needs to continue work in the upcoming years, compared to workers without a chronic

health condition. However the type of problems, obstacles, retention factors and support

needs were very similar, with problems mostly related to bodily functions, and retention

factors and needs mostly related to work‐related factors. These findings suggest that

interventions aimed to enhance sustainable working life of older workers can be similar

for persons with and without chronic health conditions and should have a central focus on

work‐related factors.

Chapter 2

40

REFERENCES

1. Council of the European union. Council conclusions on healthy and dignified ageing; 2980th employment,

social policy, health and consumer affairs council meeting. Brussel 2009.

2. The Council of the European Union. Council conclusions on Active Ageing; 3019th employment, social

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3

Towards a sustainable healthy working life: associations

between chronological age, functional age and work outcomes

Eur J Public Health. 2012 Jun;22(3):424‐9

W. Koolhaas

J.J. van der Klink

J.W. Groothoff

S. Brouwer

Chapter 3

44

ABSTRACT

Background: The aims of this study were a) to determine the relation between chronological and functional age; b) to examine the association between chronological age and work outcomes; and c) to examine the association between functional age and work outcomes. An overview of the most reported work outcomes is outlined. Methods: Chronological age refers to the calendar age; functional age was measured with perceived health status (SF‐36) and the presence of a chronic health condition. Perspectives on experienced problems, barriers, facilitators and support needs due to ageing and the Work Ability Index were gathered out as work outcomes. Results: The association of chronological and functional age of workers aged 45 years and older (n=2971) on work outcomes were significant but small, except for the presence of a chronic health condition. The presence of a chronic health condition was not related to chronological age. Older workers (60‐64 years) reported better scores on social functioning, mental health and vitality compared to workers aged 45‐59. Most reported problems due to ageing were energy decline, muscle function decline, concentration lapses and memory deterioration. Experienced barriers were concentration, work pace problems, and mobility; facilitators were support from colleagues, informal relations at work and supervisors. Individual agreement had to be met to continue working life. Conclusions: This study confirmed that both chronological and functional age were associated with a decrease in work outcomes. Workers above 60 did not experience more problems and barriers compared to workers between 45‐49 years of age. Key terms: Chronological age, functional age, older worker, chronic health condition,

sustainable healthy work participation

Chronological age, functional age and work outcomes

45

INTRODUCTION

The growing proportion of older people in the labour force stresses the need to promote a

healthy working life cycle1;2. Ageing is not simply an effect of time3‐5 but refers to many

changes in biological, psychosocial, and social functioning over time4‐7, and therefore has

an effect on the personal, organizational, and societal levels. De Lange et al.8 highlighted

this complex operationalization of ageing in the workplace, and they referred to the

approaches suggested by Sterns and Doverspike9 to conceptualize age. Five different

approaches to ageing were distinguished: chronological age, functional or performance

based age, psychosocial or subjective age, organizational age and the life span concept of

age to conceptualize ageing at work. The authors emphasized the need to pay attention to

these different types of ageing and their influence on work outcomes.

In this study we focused on chronological age and functional age and their

associations with work outcomes. Chronological age refers to one’s calendar age, which is

significantly associated with a decreased work ability10;11, and early discontinuation of

working life12‐14. Functional age refers to a worker’s performance and recognizes that

there is a variation in individual abilities and functioning through different ages7;8. In this

study we defined functional age by health status and the presence of a chronic health

condition. Chronic health condition typically begin in middle age6;15;16, and have an

adverse impact on the employability of workers17‐19. Previous studies investigated the

impact of functional age, measured with self‐related health, on the motivation to continue

to work of older workers. They found positive correlations between functional age and

motivation in older people (>60 years)7. Up to now, no studies are available which

investigate both the impact of chronological and functional age on work outcome.

Therefore, the aim of this study is to examine the relationships between ageing

and work outcomes. First, the relation between chronological and functional age was

determined. Secondly, the association between chronological age and five work outcomes

‐work ability, reported problems, barriers, facilitators and support needs due to ageing‐

was examined. Finally, the association between functional age and the five work

outcomes was examined. In addition, an overview of the most frequency reported

problems, barriers, facilitators and support needs due to ageing is outlined.

METHODS

General procedure and settings

The data of this cross‐sectional survey study were obtained from workers aged 45 years

and older. Nine companies in the northern part of the Netherlands, invited by their

occupational health physicians, were willing to participate in the study. These

Chapter 3

46

organizations represent four different sectors: health care, education, government and

industry.

A self‐administered questionnaire, consisting of 132 items on demographics,

questions about ageing, chronic diseases, health status and work ability, was sent to all

workers aged 45 years and older (N=8417). All companies enclosed a letter of

recommendation. The anonymity of respondents and confidentiality of the information

they provided were guaranteed. Four weeks after the initial mailing, all workers received a

written reminder. The data were collected in February and March 2008.

Ethical approval was sought from the Medical Ethics Committee of the University

Medical Center Groningen, which advised that, according to Dutch law, ethical clearance

was not required for this cross‐sectional study.

Measures

Age, gender and educational level were among the demographic characteristics. Three

items on occupation, sector and hours worked weekly were used to assess work

characteristics. Occupation was divided into four groups: executive, secretarial, policy; and

management. An open‐ended question was used to determine the number of hours

worked weekly under contract, and categorized in three groups: <25 hours; 25–40 hours;

and >40 hours.

Chronological age was based on the calendar age of the workers and was categorized in

five years age groups: 45‐49; 50‐54; 55‐59; 60‐64 years.

Functional age was measured with questions about perceived health status and

the presence of a chronic health condition. Health status was measured using the Dutch

version of the SF‐36 Health Survey20. The SF‐36 is a reliable and validated instrument that

consists of 8 scales covering: (i) physical functioning (10 items); (ii) role limitations

resulting from physical problems (4 items); (iii) social functioning (2 items); (iv) role

limitations resulting from emotional problems (3 items); (v) mental health (5 items); (vi)

vitality (4 items); (vii) pain (2 items); and (viii) general health (5 items). The scores of each

of the subscales range from 0 to 100, with higher scores reflecting a better health status20.

In accordance with many other studies, a chronic disease was defined as ‘the

subjective experience of long‐term irreversible disease of more than 3 months

duration’21;22. The presence of a chronic health condition was measured by asking the

respondents the following question: ‘Do you currently have a long‐term or chronic disease

of more than 3 months duration without the prospect of recovery?’ (yes/no). In addition,

the workers with a chronic health condition were asked if they experienced some degree

of hindrance due to the chronic health condition. If hindrance was reported, the worker


47

was asked to describe the degree of hindrance on a numeric scale of 0 (no hindrance) to

10 (a lot of hindrance).

Work outcomes were: work ability, problems while working due to ageing, barriers to

perform work due to ageing problems, facilitators in the work situation and support needs

to continue work. Work ability was measured by the Work Ability Index (WAI)23, a self‐

administered questionnaire comprising seven scales: (i) subjective estimation of current

work ability compared with lifetime best (0–100 points); (ii) subjective work ability in

relation to both physical and mental demands of the work (2–10 points); (iii) number of

diagnosed diseases (1–7 points); (iv) subjective estimation of work impairment due to

diseases (1–6 points); (v) sickness absenteeism during the past year (1–5 points); (vi) own

prognosis of work ability after 2 years (1 or 4 of 7 points); and (vii) psychological resources

(enjoyment of daily tasks, activity and life spirit, optimism about the future) (1–4 points).

The reliability24 and validity25 of the WAI are acceptable. Based on this WAI score, the

individual’s work ability was classified into two categories: moderate/poor (7–36 points),

and excellent/good (37–49 points)2;26.

Dichotomous (yes/no) questions were used for the other outcomes: problems,

barriers, facilitators and support needs. The first question assessed whether the workers

experienced ageing problems: ‘Do you encounter problems in working life due to ageing?’.

The next two questions concerned the barriers and facilitators to continuing working life:

‘Do you experience barriers in performing work tasks due to ageing problems?’ and ‘Are

there factors in your work which facilitate you in maintaining a sustainable working life?’.

The final question was about the support needs to continue working life in the coming

years: ‘Do you need support in the work situation to continue working life in the coming

years despite ageing?’. All respondents were asked to report a maximum of three

examples of problems, barriers, facilitators and support needs. For each question with a

‘yes’ answer, the workers were asked to describe the factors which were on top of their

mind.

Statistical analyses

A description of the sociodemographic characteristics was given by frequencies and

percentages. We used different types of analyses to examine the associations between

chronological and functional age and work outcome measures. Firstly, we examined the

association between the age‐groups (chronological age) and the five work outcome

measures by using logistic regression analyses. We adjusted for gender, education,

occupation, sector and working hours. To examine the association between functional age

Chapter 3

48

and the five work outcomes, univariate and multivariate analyses were conducted,

adjusting for chronological age, gender, education, occupation, sector and working hours.

All variables with a p‐value less than 0.20 in the univariate analyses were selected for the

multivariate analysis. To study the association between chronological age and functional

age, one‐way ANOVA test was used to compare differences between age‐groups on the

measures of functional age (health status and presence of chronic health condition).

Statistical significance was conducted for p<.05 in the logistic regression analyses, ANOVA

tests and the multivariate analysis. All analyses were carried out with the statistical

package SPSS version 16.0.


49

Table 1: Characteristics and work outcomes among workers aged 45 years and older (n=2971)

Variable n %

Age category (in years)

45‐49 856 29

50‐54 923 31

55‐59 847 28

60‐64 345 12

Female worker 1524 51

Chronic health condition 1100 37

Education

No education/ Primary School 53 2

Lower vocational education 447 16

Intermediate secondary and vocational education 673 23

Higher vocational education and university 1717 59

Sector

Health care 1207 41

Education 1261 42

Production 274 9

Government 229 8

Occupation

Executive 1782 61

Secretarial / Administrative 374 13

Policy 376 13

Management 395 13

Working hours

< 24 694 24

25‐40 2194 74

> 40 55 2

Work outcomes

Problems while working due to ageing (yes) 1236 42

Barriers to perform work due to ageing problems (yes) 735 25

Facilitators in the work situation (yes) 2419 82

Support needs to continue work (yes) 1138 38

Work ability score

Excellent/good 2213 75

Moderate/poor 751 25

Chapter 3

50

RESULTS

Characteristics sample

A total of 8417 workers aged 45 years and older from the nine included organizations

were invited to participate in the study, and 3008 returned the self‐administered

questionnaire (36% response). Because age is one of the main variables in our analyses,

we excluded 37 workers who did not report their age. The response rate differed across

the nine organizations (28‐55%), and seems to be associated with the number of

employees in the organizations. The response rate in the two largest organizations (more

than 4000 workers) was below 36%. All other organizations scored around 36% or higher.

The mean age of the workers was 53.4 years (SD 5.0) ranging from 45‐64 years of age.

Most workers were highly educated (59%) and most of them were working in the sectors

education (42%) and health care (41%). The presence of a chronic health condition was

reported by 37% of the workers. Most frequently reported chronic health conditions were

musculoskeletal diseases (n=878, 25%), followed by mental health conditions (n=390,

11%), neurological or sensory disease (n=351, 10%), and cardiovascular diseases (n=99,

9%). Of those workers who reported the presence of a chronic health condition, 50%

reported some degree of hindrance due to the chronic health condition. The degree of

hindrance due to the chronic disease, expressed on a numeric scale of 0 (no hindrance) to

10 (a lot of hindrance), was on average 6.7 (SD 2.4). With regard to the work outcome

measures, the work ability of 75% (n=2213) of the workers was excellent/good. In total

42% (n=1236) workers reported problems while working due to ageing, 25% (n=735)

experienced barriers in performing work tasks, 82% (n=2419) reported facilitators and

38% (n=1138) of the workers reported support needs to continue work in the next coming

years. Detailed information about these characteristics are presented in Table 1.

The association between chronological age and functional age

Chronological age was not significantly associated with the presence of a chronic health

condition (p=0.34). All other outcome measures of functional age differ significantly

between the age groups (p<.05) (Table 2). Post‐hoc analyses indicated that the youngest

workers (45‐49 year) scored significantly higher on physical functioning compared to the

other groups (p<.02), and the general health of these workers was significant better than

workers aged 55‐59 years (p<.04). The workers in the oldest age group (60‐64 years)

reported significantly higher scores on the subscales social functioning (p<.05), mental

health (p<.05) and vitality (p<.001) compared to the other age‐groups.

51

Table 2: Influen

ce of chronological age, based

on 5‐years age groups, on functional age

Chronological age

(years)

Fp

Functional age

Total

(n=2971)

45‐49

(n=856)

50‐54

(n=923)

55‐59

(n=847)

60‐64

(n=345)

Mean

scores

Physical functioning

90.38

91.84

89.68

88.35

88.98

8.407

<.001*

Social functioning

83.94

83.87

82.83

83.42

88.38

6.465

<.001*

Men

tal health

69.85

69.78

69.03

69.84

72.26

5.895

0.001*

Vitality

62.80

62.09

61.90

62.92

66.73

10.733

<.001*

Gen

eral health

69.74

71.12

69.03

68.76

70.63

3.37

0.018*

Frequency

Presence chronic health condition (%)

1113 (37%)

292 (34%)

347 (38%)

334 (39%)

117 (34%)

0.341

*p<.05

52

Table 3: A

ssociation between chronological age and problems, barriers, facilitators, support needs and work ability, adjusted

for

gender, education, occupation, sector and working hours

Age

groups

(years)

Problems while

working due to ageing

(reference=n

o)

Barriers to perform

work due to ageing

(reference=n

o)

Facilitators in

the work

situation

(reference=n

o)

Support need

s to

continue work

(reference=n

o)

Excellent or good work

ability (reference=

moderate/ poor)

OR

95% CI

OR

95% CI

OR

95% CI

OR

95% CI

OR

95% CI

45‐49

(referen

ce)

1.00

1.00

1.00

1.00

1.00

50‐54

1.343*

1.101‐1.638

0.982

0.742‐1.396

0.732*

0.555‐0.965

1.301*

1.065‐1.590

0.683*

0.538‐0.867

55‐59

1.641*

1.337‐2.013

0.964

0.754‐1.427

0.583*

0.442‐0.768

1.389*

1.130‐1.709

0.529*

0.416‐0.673

60‐64

1.177

0.893‐1.551

0.801

0.805‐1.938

0.585*

0.412‐0.831

0.928

0.697‐1.235

0.661*

0.481‐0.908

* p<0.05

OR = odds ratio, CI =

confiden

ce interval


53

Chronological age and work outcome measures

In table 3 the results of the association between chronological age and experienced

problems, barriers, facilitators, support needs and work ability are presented. Workers in

the age‐groups 50‐54 years (OR 1.34; 95% CI 1.10‐1.64) and 55‐59 years (OR 1.64; 95% CI

1.34‐2.01) reported significant more problems while working due to ageing compared to

workers aged 45‐49 years, but also reported more support needs to continue working life

in the next coming years (respectively OR 1.30; 95% CI 1.07‐1.59 and OR 1.39; 95% CI 1.13‐

1.71). Workers between 50‐64 years of age experienced significantly less facilitators in the

work situation compared to the youngest age group (OR between 0.58‐0.73). Workers

above 50 years of age had significant more chance on a moderate/poor work ability (OR

between 0.53 and 0.68). However, the chance of moderate/poor work ability was

significantly lower in the oldest age group compared to the workers between 55‐59 years

of age. No significant differences between age‐groups were found for barriers to perform

work.

Functional age and work outcome measures

Table 4 gives the crude and multivariate odds ratios and 95% confidence intervals on

measures of functional age on work outcomes. Univariate logistic regression analyses

showed that the measures of functional age (health status subscales and presence of

chronic health condition) were significantly associated with all work outcome measures

(p<.20), except for the association between the presence of a chronic health condition and

experienced facilitators (p=0.44). In the multivariate analyses most health status subscales

(except mental health) and the presence of a chronic health condition remained

statistically significant. Higher scores on vitality were associated with less problems due to

ageing (OR 0.98; 95%CI 0.97‐0.98), less barriers to perform work (OR 0.97; 95%CI 0.96‐

0.99), more perception of facilitators (OR 1.02; 95%CI 1.00‐1.03), less support needs to

continue working life (OR 0.97; 95%CI 0.96‐0.98) and more chance of excellent/good work

ability (OR 1.04; 95%CI 1.02‐1.05). Having a chronic health condition resulted in more

chance to report problems due to ageing (OR 1.52; 95% CI 1.26‐1.83), barriers to perform

work (OR 2.01; 95% CI 1.51‐2.68), more chance to report experienced support needs to

continue working life (OR 1.52; 95% CI 1.26‐1.84) and less chance to score moderate/poor

work ability (OR 0.35; 95% CI 0.27‐0.45). Mental health did not remain significantly in the

final multivariate model for all work outcome measures.

Chapter 3

54

Table 4: Association between functional age and problems, barriers, perceptions, support

needs, and work ability adjusted for chronological age, gender, education, occupation,

sector and working hours.

Univariate Multivariate

OR 95%CI p OR 95%CI p

Problems while working due to ageing (reference=no)

Physical functioning1 0.973 0.967‐0.978 <.001* 0.993 0.986‐1.000 0.048**

Social functioning1 0.977 0.973‐0.981 <.001* 0.999 0.993‐1.004 0.664

Mental health1 0.962 0.956‐0.969 <.001* 0.991 0.981‐1.000 0.060

Vitality1 0.957 0.951‐0.962 <.001* 0.975 0.966‐0.984 <.001**

General health1 0.970 0.965‐0.975 <.001* 0.991 0.985‐0.997 0.002**

Chronic health condition 2.450 2.088‐2.875 <.001* 1.518 1.261‐1.828 <.001**

Barriers to perform work due to ageing (reference=no)

Physical functioning1 0.948 0.937‐0.959 <.001* 0.976 0.964‐0.988 <.001**

Social functioning1 0.963 0.956‐0.970 <.001* 0.983 0.974‐0.992 <.001**

Mental health1 0.964 0.955‐0.974 <.001* 1.004 0.989‐1.020 0.574

Vitality1 0.946 0.937‐0.956 <.001* 0.973 0.958‐0.987 <.001**

General health1 0.964 0.956‐0.971 <.001* 0.997 0.987‐1.008 0.600


Facilitators in the work situation (reference=no)

Physical functioning1 1.005 0.999‐1.012 0.123* 0.996 0.988‐1.004 0.301

Social functioning1 1.011 1.007‐1.016 <.001* 1.005 0.998‐1.012 0.158

Mental health1 1.018 1.010‐1.025 <.001* 1.001 0.990‐1.013 0.846

Vitality1 1.020 1.013‐1.027 <.001* 1.015 1.004‐1.026 0.008**

General health1 1.010 1.004‐1.016 0.001* 1.001 0.994‐1.009 0.747

Chronic health condition 0.922 0.750‐1.134 0.443 ‐‐‐‐ ‐‐‐‐ ‐‐‐‐

Support needs to continue work (reference=no)

Physical functioning1 0.979 0.973‐0.984 <.001* 1.001 0.944‐1.008 0.819

Social functioning1 0.974 0.970‐0.978 <.001* 0.993 0.987‐0.998 0.012**

Mental health1 0.962 0.956‐0.969 <.001* 0.996 0.987‐1.006 0.454

Vitality1 0.955 0.949‐0.961 <.001* 0.970 0.962‐0.979 <.001**

General health1 0.973 0.968‐0.978 <.001* 0.995 0.989‐1.001 0.091



55

Table 4 continued Univariate Multivariate

OR 95%CI p OR 95%CI p

Excellent or good work ability (reference= moderate/poor)

Physical functioning1 1.078 1.069‐1.087 <.001* 1.030 1.021‐1.039 <.001**

Social functioning1 1.066 1.060‐1.072 <.001* 1.030 1.022‐1.038 <.001**

Mental health1 1.072 1.064‐1.081 <.001* 1.004 0.991‐1.017 0.572

Vitality1 1.100 1.090‐1.109 <.001* 1.034 1.020‐1.047 <.001**

General health1 1.090 1.083‐1.100 <.001* 1.047 1.038‐1.057 <.001**

Chronic health condition 0.122 0.100‐0.149 <.001* 0.351 0.271‐0.451 <.001** 1Higher scores on the scale means a better physical functioning, social functioning, mental health, vitality or general health * p<.20 **p<.05 OR = odds ratio, CI = confidence interval

Overview of the problems, barriers, facilitators and support needs

In the group of workers (42%; n=1236) who reported problems while working due to

ageing, the most frequently reported problems were energy decline (fatigue) (17%),

muscle function decline (strength and endurance) (11%), concentration lapses (10%), and

memory deterioration (8%). Most experienced barriers to perform work tasks, reported by

25% of the workers (n=735), were tasks which require concentration (22%), lifting and

carrying objects (11%), and work pace (9%). Most reported facilitators, by 82% (n=2419) of

the workers, were support from colleagues (19%), formal relations in work (e.g. clients,

patients or students) (12%) and the supervisor (8%). The workers reported predominantly

support needs (38%, n=1138) with regard to services, systems and policies at the company

level (53%), for example adjustments in tasks and functions, individual agreements about

working hours and days, and variety and autonomy.

Chapter 3

56

DISCUSSION

The results of this study showed that chronological age and functional age are related,

although the presence of a chronic health condition was not influenced by age. Workers

with higher chronological age, especially between 50 and 59 years, experienced more

problems due to ageing, fewer facilitators to continue working life and reported

frequently more support needs to continue work in the next coming years compared to

the younger ones. In addition, the work ability scores decreased by age. Experienced

barriers to perform work were not associated with chronological age. The results of this

study may suggest that employers can do far more to help older workers to remain in the

workplace towards a sustainable healthy working life.

Workers in the oldest age group (60‐64) reported higher scores on social functioning,

mental health and vitality compared to the youngest age group (45‐49). Although the

general health of workers aged 55‐59 years was significantly lower than the mean scores

of the workers in the youngest age group, no significant difference was found for workers

in the oldest age group. Also no significant difference was found for the presence of a

chronic health condition between the two age groups. Based on the literature, it was

expected that older workers had lower scores on measures of health status6 and those

workers experienced frequently more chronic health conditions15;16. This finding might be

explained by the healthy worker effect, a phenomenon which is often studied in

occupational cohorts27;28. Workers, especially the older workers, usually exhibit better

health conditions than the general population because severely ill and chronically disabled

are ordinary excluded from employment. This healthy worker effect might also explain

why we found no significant difference between the oldest and youngest age group in the

association between chronological age and work outcomes. The workers between 60 and

64 who are still working, might be a very select, relatively healthy group of the general

population of this age. Because of this selection bias due to the healthy worker effect, the

results in this report are probably an underestimation of the problems in the entire age

group.

Functional age was significant associated with work outcomes; the associations

were significant, but small odds ratios were found, except for the presence of a chronic

health condition. Mental health did not contribute to experienced problems, barriers,

facilitators, support needs, and work ability. The impact of the presence of a chronic

health condition was reduced by the other measures of functional age. Due to ageing, 42%

of the workers aged 45 years and older reported problems in the work participation, and

37% reported a chronic health condition. Although most workers (82%) experienced

facilitators in the work situation, 25% of the workers experienced barriers to perform


57

work as well. To continue work in the next coming years 38% of the workers experienced

support needs.

A strength of the study is that it was based on a considerable sample size of

workers with various occupational activities (e.g. heavy physical labour, back office, health

care, teaching and cleaning), employed in different companies. While this study had the

advantage of using a population‐based sample, there are some limitations in generalizing

these findings.

The overall response rate of 36% at baseline was regarded to be reasonable for an

anonymous survey in the working population, but results related to selective participation

cannot be ruled out. Because of the anonymous study design, we were not able to

investigate the characteristics of the non‐responders properly. Nevertheless, we believe

there is no reason to expect that workers with problems due to functional age or a chronic

health condition returned the questionnaire less frequently than workers without

problems. The questionnaire addressed a variety of themes, and did not emphasize

functional age or chronic health condition.

A second issue concerns the self‐reporting nature of the study because the perception of

workers’ responses could not be externally validated. As a result, some bias may exist in

the classification of respondents on the basis of self‐reported data, resulting in an

underestimation of the differences and associations under study. However, it is known

from literature that the self‐reporting of health status and of certain physical chronic

diseases (diabetes, cardiovascular disease, musculoskeletal and respiratory problems) is

reasonably reliable29. Therefore, we do not expect that the self‐reporting of health and

problems due to ageing introduced any significant bias for this kind of health conditions.

However, this expectation is based on a limited number of studies concerning physical

conditions and might not self‐evidently be generalizable to other physical or mental health

conditions.

Finally, the current study does not distinguish between specific chronic health

conditions because of the lack of knowledge of the severity and limitations of the

conditions. Not distinguishing between workers suffering from various chronic health

conditions in relation to a sustainable working life is supported by Detaille et al. among

physically ill workers30;31. They showed that different groups of chronically ill workers

were experiencing the same bottlenecks, although their priority varied. These findings

support the idea that the impact of chronic health conditions may be applicable for

workers in general, in the Netherlands and other industrialized countries.

An overview was given of the most frequency reported problems, barriers,

facilitators and support needs due to ageing. We used the responses based on open‐

Chapter 3

58

ended survey items and calculated for each work outcome separately which example of

problems, barriers, facilitators and support needs were reported most frequently in our

sample. We found that factors to enhance working life were reported at both personal

and organizational level. The next step for research is to outline in more detail analysis on

subgroup level (e.g. differences between age groups or workers who report problems

while working due to ageing) on the most frequently experienced barriers to perform

work, facilitators in the work situation and support needs to continue working life. Based

on qualitative analyses, a list of relevant factors can be developed. Insight in these factors

may be useful for developing interventions and strategies towards a sustainable healthy

working life.

KEY POINTS

Due to ageing, 42% of the workers aged 45 years and older reported problems

while working, 37% reported a chronic health condition.

The presence of a chronic health condition was not influenced by chronological

age in workers aged 45 years and older.

Increased chronological age resulted in more experienced problems, more

support needs, less experienced facilitators and decreased work ability.

With respect to functional age, predominantly a chronic health condition was

associated with more problems, more barriers, more support needs and lower

work ability scores.

Reported problems in work functioning increased with chronological age, but

workers in the aged group 60‐64 years did not report more problems and barriers

compared to workers between 45‐49 years of age.


59

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employers: a review of the literature. Pharmacoeconomics. 2009;27(5):365‐78.

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questionnaire. Occup.Med. 2002;52(4):177‐81.

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26. Tuomi, K., Ilmarinen, J., Jahkola, A., et al. Work ability Index. 2nd revised edn. Finnish Institute of

Occupational Health. Helsinki 1998.

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2005;78(4):270‐278.

30. Detaille SI, Haafkens JA, Hoekstra JB, van Dijk FJH. What employees with diabetes mellitus need to cope

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4

Chronic health conditions and work ability in the ageing

workforce: the impact of work conditions, psychosocial factors

and perceived health

Accepted Int Arch Occup Environ Health. 2013 [Epub ahead of print]

W. Koolhaas

J.J. van der Klink

M.R. de Boer

J.W. Groothoff

S. Brouwer

Chapter 4

62

ABSTRACT

Purpose: The aim of this study was to determine the influence of work conditions,

psychosocial factors and perceived health on the association between the presence of a

chronic health condition and (single item) work ability among workers aged 45 years and

older. In addition, we aimed to examine variables associated with work ability for workers

with and without a chronic health condition separately.

Methods: The data of this cross‐sectional study were obtained from 5247 workers aged

45 years and older in five different work sectors. Work ability was assessed with the first

item of the Work Ability Index. The presence of a chronic health condition was assessed by

self‐report. Independent variables in the multivariable linear regression analysis were

work conditions, psychosocial factors and perceived health status.

Results: The presence of a chronic health condition was negatively associated with work

ability (B = ‐0.848). The strength of this association slightly attenuated after subsequently

adding individual characteristics (B = ‐0.824), work conditions (B = ‐0.805) and more so

after adding psychosocial factors (B = ‐0.704) and especially perceived health variables

(B = ‐0.049) to the model. Variables associated with work ability for workers with and

without a chronic health condition were similar.

Conclusion: Perceived health and psychosocial factors, rather than work conditions,

explained the association between the presence of a chronic health condition and work

ability. Substantial differences of variables associated with work ability for workers with

and without a chronic health condition were not found. Based on the lower mean scores

for workers with a chronic health condition for work ability as well for predictors, these

workers might have the most benefit by a policy focussing on enhancing these associated

variables.

Key words: Ageing workers, Chronic health condition, Perceived health, Psychosocial

factors, Work ability, Work conditions

Chronic health conditions and work ability

63

INTRODUCTION

There is ample evidence of the burden of chronic conditions on health and work

outcomes1‐4. Given the fact that the prevalence of chronic conditions increases with age

and that person will be required to work until higher ages, the prevalence of chronic

conditions in the working population can be expected to increase even further5,6. This

might hamper the contribution of large parts of the working age population to the work

process, especially for workers aged 45 years and older. A recent study showed that in the

Dutch working population of 45 years of older one in three workers indicated a chronic

health condition7. Chronic health conditions have an adverse impact on the employability

of workers8‐10. Previous research about differences between workers with and without a

chronic health condition shows that workers with a chronic health condition experiences

more problems due to ageing, more barriers to perform work, more support needs and

lower work ability scores7. For sustainable employability it is crucial that work demands

are adjusted to the health status and abilities of the individual worker.

Within this framework, the concept of work ability has been developed as an

important multi‐factorial concept that can be used to identify workers at risk for an

imbalance between health, personal resources and work demands11,12. The work ability

concept is based on the assumption that work ability is determined by an individual’s

perception of the demands at work and the ability to cope with them. Previous research

showed that work ability, measured with the Work Ability Index (WAI), is negatively

influenced by older age, high physical work demands, high psychosocial work demands,

unhealthy lifestyle and a poor physical fitness12‐16. It is also known from literature that it is

crucial to promote social support and networks at the workplace and in private life, as well

as a coping‐oriented approach to health issues and social life in order to strengthen work

ability among female employees in elderly care17. Furthermore, lower work ability levels

have been shown to result in decreased work performance, productivity loss, long‐term

sickness absence and early exit from work7,10,13,18‐21. In addition, several studies have

established a strong association between perceived health status and work ability18,22‐26.

Although previous studies confirmed the associations between psychosocial,

work‐related factors and perceived health on work ability in different occupational

populations and age groups, to our knowledge, none of these studies so far have studied

the impact of these potential explanatory factors on the association between the

presence of a chronic health condition and work ability. One of the underlying reasons

might be that the WAI is an instrument that contains many disparate questions more or

less indirectly measuring work ability (eg. relating to diagnosis of chronic conditions and

sick leave). This may have implications when the WAI is used among workers already on

Chapter 4

64

sick leave; also, it may give too much weight to diagnoses not necessarily related to work

ability18. As a result, the single‐item question on work ability has often replaced the WAI in

clinical and occupational practice18,27,28. Ahlstrom found strong associations between the

WAI and the single‐item question with sick leave, health and symptoms among long‐term

sick‐listed women working in human service organizations. Moreover, they found strong

predictive value for the degree of sick leave and health‐related quality of life for the

single‐item question. Although further validation studies are still lacking the single‐item

question on work ability may be a good alternative to the WAI. The benefits for using the

single‐item question in our study is that it could be used as an indicator for assessing the

status of work ability among workers with and without a chronic health condition without

given too much weight to diagnoses not necessarily related to work ability when using the

WAI.

The main purpose of this study is to determine the impact of work conditions,

psychosocial factors, and perceived health on the association between the presence of a

chronic health condition and work ability among workers aged 45 years and older. In

addition, variables associated with work ability level will be examined for workers with

and without a chronic health condition separately.

METHODS

Design and study population


and older who worked in ten different organisations in the Netherlands. These

organisations represent five different sectors: health care, education, government,

production industry and telecommunication. A self‐administered questionnaire was sent

to all participants (n=13897). All companies enclosed a letter of recommendation. The

anonymity of respondents and confidentiality of the information they provided were

guaranteed. Four weeks after the initial mailing, all workers received a written reminder.

Information from questionnaires was available from 5730 workers. The overall response

was 40% varying from 28% (health care) to 58% (production) across organisations. 483

workers (8%) were excluded from the analyses because of incomplete data. These workers

with missing values had significant lower mean scores on years paid work (‐1.35 years)

and active coping (‐0.60 points) and consisted of a significantly higher percentages of

women (42% vs 33%), lower educated workers (29% vs 22%), executive workers (56% vs

46%), production workers (18% vs 4%), workers with physical work (15% vs 6%) and

lower percentages of workers with mental work (55% vs 65%) or working in the sector

telecommunication (31% vs 49%) than those workers included in the study.


65

Ethical approval was sought from the Medical Ethics Committee of the University Medical

Center Groningen, which advised that, according to Dutch law, ethical clearance was not

required for this cross‐sectional study.

Work ability

Self‐reported work ability was measured by the first item of the work ability index:

“current work ability compared with the lifetime best”. The value 0 represents ‘completely

unable to work’ and 10 the ‘work ability at its best’29. Previous research has established

that the single‐item question on work ability can be used as a reliable indicator for

assessing the status and progress of work ability16,18,21,28.

Chronic health condition

We defined a chronic disease as ‘the subjective experience of a long‐term irreversible

disease of more than 3 months duration’ which is in accordance with many other

studies7,30,31. It was assessed by asking the respondents the following question: ‘Do you

currently have a long‐term or chronic disease of more than 3 months duration without the

prospect of recovery?’ (yes/no).

Individual characteristics

Data of age, gender and education were collected by questionnaire. Age was based on the

calendar age of the workers. The highest education level successfully completed was

categorized into low (no education, primary or secondary education) and high (post‐

secondary education).

Work conditions

Organisations were categorized in the sectors health care, education, government,

telecommunication and production. Participants were asked in which of the following

occupational areas they worked: executive, secretarial, policy, or management. The

duration of the current function and years of paid work were reported in years. A

dichotomous (yes/no) question was used to assess shift work. Self‐reported work type

assessed with a single questions, based on the question in the WAI, was used to classify

workers into physical, mental or both.

Psychosocial factors

Perceived work attitude was measured with the Dutch language version of the Work

Involvement Scale (WIS‐DLV), reflecting the degree to which a person wants to be

Chapter 4

66

engaged in work32. The questionnaire consists of six items with responses on a 1‐4 point

scale (strongly disagree, disagree, agree, and strongly agree). Higher scores on the WIS‐

DVL indicate a more positive attitude towards work. The internal consistency (Cronbach’s

alpha) of the WIS‐DLV in this study was 0.72.

The Utrecht Coping List (UCL) was used to assess styles of coping33. This

questionnaire was designed to measure the coping strategies people use in stressful

situations. In this study we used the short version of the original 47‐item Utrecht Coping

List (UCL, 1995) which include a selected number of dimensions and items and consisting

of three scales: (1) active problem‐focusing (five items), (2) expression of emotions (four

items), and (3) avoidance behaviour (four items). We used the active and passive coping

styles in this study which were shown to be important constructs in other work and health

related studies34‐36. The internal consistencies as well as the test‐retest reliabilities have

been shown to be satisfactory33. The internal consistencies found for active, expression of

emotions and avoiding focused coping strategies in this study were 0.84, 0.70, and 0.71

respectively.

Perceived support was measured with a self‐constructed scale reflecting a

person’s perception of social support. The 14 items were answered on a 5‐point Likert

scale (totally disagree to totally agree). A confirmatory factor analysis was carried out in

three subscales: 1) co‐workers support (two items), 2) community support (six items), and

3) organisational support (six items). Higher scores indicate more support for all scales.

The internal consistencies for co‐workers, community, and organisational support in this

study were, 0.66, 0.70, and 0.72 respectively.

Health status

Perceived health status was assessed with the Dutch version of the SF‐36 Health Survey

consisting of eight multi‐item scales: physical functioning, role limitations due to physical

health problems, pain, general health perceptions, vitality, social functioning, role

limitations due to emotional problems, and mental health37. Higher scores indicate higher

levels of functioning and health (range 0–100). The internal consistency of the subscales

was between the 0.74 (subscale general health) and 0.89 (subscales role limitations for

physical problems and role limitations for emotional problems).


Multivariable linear regression analysis were performed to examine the impact of the

potential explanatory factors (i.e. work conditions, psychosocial factors, and perceived

health status) on the association between the presence of a chronic health condition and


67

work ability. To estimate to what extent this association could be explained by the

predictors, multiple linear regressions were performed using a forward stepwise method.

In this method, predictors were entered (forwards) in blocks. In model 1 chronic health

condition was entered. The individual characteristics were entered in model 2, followed by

the work conditions in model 3, the psychosocial factors in model 4 and the perceived

health status variables in model 5. To determine the impact of the work conditions,


chronic health condition and work ability, we included all variables which were

significantly associated in the stepwise analyses of model 1 to 5 in all models.

Subsequently, we separately added the potential variables to the multivariate model

which were not statistically significant in the univariate analysis to determine their

association with the outcome measure in the presence of other prognostic factors.

To determine variables associated with work ability for workers with and without a

chronic health condition, analyses were stratified by the presence of a chronic health

condition. All significant variables in the multivariable model for one of the groups were

included in the models for other groups as well in order to provide an appropriate

comparison. The level of significance for all statistical tests was set at an alpha of 0.05 (2‐

sided) using the Statistical Package for the Social Sciences (SPSS, Inc, Chicago, IL, USA),

version 16.0.

RESULTS

The study population included 3508 men (67%) and 1734 women (33%) of the five

different sectors; production (4%), education (23%), health care (20%), government (4%)

and telecommunication (49%). The mean age of the workers was 53.0 years (SD 4.4)

ranging from 45 to 64 years of age. The majority (77%) of the workers was highly

educated. The mean score on work ability was 8.1 (SD 1.4, median 8.0) ranging from 0 to

10. Detailed information about these characteristics is presented in Table 1. Thirty‐five per

cent of the workers had a chronic health condition, with the highest prevalence for

musculoskeletal conditions (n=1497, 81%), neurological or sensory disease (n=654, 35%),

and cardiovascular diseases (n=634, 34%) (data not shown).

68

Table 1: B

aseline characteristics of the study population with subgroup analyses for workers with and without a chronic health

condition

Characteristics

Total population

(n = 5247)

Without a chronic health

condition (n = 3395)

With a chronic health


N

Mean

(SD

) (%

) N

Mean

(SD

) (%

) N

Mean

(SD

) (%

)

Age (yr)

53.0 (4.4)

52.9 (4.5)

53.3 (4.3)

Gender

Male

3508

67

2348

69

1160

63

Fem

ale

1739

33

1047

31

692

37

Education

Low

1181

23

692

20

489

26

High

4066

77

2703

80

1363

74

Chronic health condition (yes)

1852

35

1852

100

Work conditions

Occupation

Executive

2429

46

1512

45

917

50

Secretarial

1063

20

658

19

405

22

Policy

1009

20

695

20

314

17

Managem

ent

746

14

530

16

216

11

Sector

Production

192

4118

374

4

Education

1170

23

743

22

427

23

Health care

1099

20

676

20

423

23

Governmen

t212

4143

469

4

Telecommunication

2574

49

1715

51

859

46

69

Table 1: continued

Characteristics

Total population

(n = 5247)





N

Mean

(SD

) (%

)N

Mean

(SD

)(%

)N

Mean

(SD

)(%

)

Curren

t function (years)

21.6 (11.6)

21.3 (11.6)

22.1 (11.6)

Paid work (years)

31.9 (7.0)

31.6 (6.9)

32.4 (7.0)

Work type

Men

tal

3446

66

2322

68

1124

61

Physical

311

6180

6131

7

Both m

ental and physical

1490

28

893

26

547

32

Shift work (yes)

586

11

368

11

218

12


Work attitude

66.1 (19.8)

67.5 (19.1)

63.4 (20.9)

Coping

Active problem focusing

14.8 (2.6)

14.8 (2.6)

14.7 (2.6)

Expression of em

otions

8.4 (1.9)

8.4 (1.8)

8.6 (2.0)

Avoidance beh

aviour

8.2 (2.0)

8.1 (2.0)

8.3 (2.0)

Support

Co‐w

orkers

4.2 (2.0)

4.1 (2.0)

4.4 (2.0)

Community

24.0 (4.7)

24.4 (4.5)

23.4 (4.8)

Organisational

19.5 (4.0)

19.6 (3.9)

19.4 (4.3)

Perceived health status


90.2 (14.2)

94.3 (9.6)

82.7 (17.7)

Social functioning

84.8 (19.8)

89.8 (15.5)

75.7 (23.2)

Role limitations from physical

problems

77.2 (36.3)

86.2 (28.9)

60.7 (42.1)

70

Table 1: continued

Characteristics

Total population

(n = 5247)





N

Mean

(SD

) (%

)N

Mean

(SD

)(%

)N

Mean

(SD

) (%

)

Role limitations from emotional problems

81.5 (35.2)

86.4 (30.7)

72.6 (40.7)

Men

tal health

70.1 (12.3)

72.1 (10.7)

66.4 (13.9)

Vitality

63.3 (14.2)

66.6 (12.6)

57.2 (15.0)

Pain

84.5 (19.2)

91.1 (14.4)

72.5 (21.0)

Gen

eral health

69.8 (17.3)

75.2 (14.0)

59.9 (18.4)

Work ability

Work ability score single item

8.1 (1.4)

8.4 (1.2)

7.5 (1.6)


71

Table 2 shows that the presence of a chronic health condition was negatively associated

with work ability (B = ‐0.848). The effect of the individual characteristics and work

conditions on this association was small (B = ‐0.805), but the regression coefficient

attenuated to ‐0.704 after addition of the psychosocial factors. The presence of a chronic

health condition explained 8.2% of the variance in work ability. The proportion explained

variance increased after addition of the individual and work conditions with respectively

1.8% and 1.4%. The R‐square change after addition of the psychosocial factors in model 4

was 8.5% resulting in a total explained variance of 19.7% in work ability.

After adding the perceived health variables, the association between the presence of a

chronic health condition and work ability was strongly attenuated (B = ‐0.049) and ceased

to be statistically significant. The total explained variance of work ability of this final model

was 40.1%.

Analyses stratified by the presence of a chronic health condition are shown in Table 3. For

both workers with and without a chronic health condition psychosocial factors and

perceived health status were associated with work ability. Small, but significant

associations with very low B‐values, were found for workers suffering from a chronic

health condition for occupation and work type, whereas gender and age were significant

individual factors for workers without a chronic health condition. 42.8% of the variance in

work ability for workers suffering from a chronic health condition was explained by the

factors in the model, while these factors explained 28.7% of the variance for workers

without a chronic health condition.

72

Table 2: M

ultivariabele association of the presence of a chronic health condition, w

ork conditions, psychsocial factors

and perceived

health on work ability

Model 1

Model 2

Ba

Beta

b

95% CI for B

Ba

Beta

b95% CI for B

Lower

bound

Upper

bound

Lower

bound

Upper

bound

Presence of a chronic health condition

Chronic health condition (reference = no)

‐0.848 ¥

‐0.287

‐0.924

‐0.771

‐0.824 ¥

‐0.279

‐0.900

‐0.748


Age (yr)

‐0.027 ¥

‐0.084

‐0.035

‐0.018

Gender (referen

ce = m

ale)

0.063

0.021

‐0.014

0.140

Education (reference = low)

0.324 ¥

0.096

0.236

0.411

Work conditions

Occupation: secretary vs executive

Occupation: p

olicy vs executive

Occupation: m

anagem

ent vs executive

work type: physical vs. m

ental job dem

ands

work type: both physical and m

ental vs

men

tal job dem

ands

Total R

‐square (%)

8.2

10

R‐square change (%)

8.2

1.8

n

5247

5247

*p<.05; §p<.01; ¥p<.001, a

B, unstandardized

regression coefficient, b beta, standardized

regression coefficient

73

Table 2:continued

Model 3

Model 4

Ba

Beta

b

95% CI for B

Ba

Beta

b95% CI for B

Lower

bound

Upper

bound

Lower

bound

Upper

bound


Chronic health condition (reference = no)

‐0.805 ¥

‐0.273

‐0.880

‐0.729

‐0.704 ¥

‐0.239

‐0.777

‐0.632


Age (yr)

‐0.025 ¥

‐0.079

‐0.033

‐0.017

0.002

0.008

‐0.006

0.011

Gender (referen

ce = m

ale)

0.124 §

0.041

0.044

0.204

0.064

0.021

‐0.013

0.141


0.230 ¥

0.068

0.139

0.322

0.130 §

0.038

0.041

0.218

Work conditions

Occupation: secretary vs executive

0.048

0.014

‐0.055

0.150

0.146 §

0.042

0.048

0.245

Occupation: p

olicy vs executive

0.147 §

0.041

0.042

0.253

0.115 *

0.032

0.014

0.216

Occupation: m

anagem

ent vs executive

0.351 ¥

0.087

0.236

0.465

0.195 ¥

0.048

0.084

0.306

Work type: physical vs. m

ental job dem

ands

‐0.419 ¥

‐0.070

‐0.585

‐0.254

‐0.293 ¥

‐0.049

‐0.453

‐0.134

Work type: both phy./m

en.vs men.Jobdem.

‐0.066

‐0.021

‐0.155

0.023

‐0.011

‐0.003

‐0.095

0.074


Work attitude

0.007 ¥

0.105

0.005

0.009

Coping: active problem focusing

0.076 ¥

0.139

0.062

0.090

Coping: avoidance beh

aviour

‐0.068 ¥

‐0.097

‐0.085

‐0.051

Co‐w

orker support

‐0.053 ¥

‐0.075

‐0.070

‐0.035

Community support

0.055 ¥

0.182

0.046

0.064

Organisational support

‐0.006

‐0.017

‐0.015

0.003

Total R

‐square (%)

11.3

19.7

R‐square change (%)

1.4

8.5

n

5247

5247

Chapter 4

74

Table 2: continued

Model 5

Ba Betab 95% CI for B

Lower

bound

Upper

bound


Chronic health condition (reference = no) ‐0.049 ‐0.017 ‐0.122 0.024


Age (yr) ‐0.012 § ‐0.038 ‐0.02 ‐0.005

Gender (reference = male) 0.087 * 0.029 0.020 0.155

Education (reference = low) 0.092 * 0.027 0.016 0.169

Work conditions

Occupation: secretary vs executive 0.080 0.023 ‐0.006 0.165

Occupation: policy vs executive 0.021 0.006 ‐0.067 0.109

Occupation: management vs executive 0.084 0.021 ‐0.013 0.180

Work type: physical vs. mental job demands ‐0.195 § ‐0.033 ‐0.334 ‐0.057

Work type: both phy./men. vs men. Job dem. s 0.024 0.008 ‐0.050 0.097


Work attitude 0.005 ¥ 0.075 0.004 0.007

Coping: active problem focusing 0.038 ¥ 0.069 0.025 0.050

Coping: avoidance behaviour ‐0.028 ¥ ‐0.041 ‐0.044 ‐0.013

Co‐worker support ‐0.008 ‐0.011 ‐0.023 0.007

Community support 0.028 ¥ 0.092 0.020 0.036

Organisational support ‐0.008 * ‐0.024 ‐0.016 ‐0.001


Physical functioning 0.008 ¥ 0.082 0.005 0.011

Social functioning 0.007 ¥ 0.102 0.005 0.010

Role limitations from physical problems 0.004 ¥ 0.104 0.003 0.005

Role limitations from emotional problems 0.002 ¥ 0.055 0.001 0.003

Mental health 0.005 § 0.048 0.002 0.009

Vitality 0.017 ¥ 0.176 0.014 0.021

Pain 0.003 * 0.039 0.001 0.005

General health 0.010 ¥ 0.119 0.007 0.012

Total R‐square (%) 40.1

R‐square change (%) 20.5

n 5247

*p<.05; §p<.01; ¥p<.001, a B, unstandardized regression coefficient, b beta, standardized regression

coefficient

75

Table 3: M

ultivariabele association of work conditions, psychosocial factors and perceived

health status on work

ability for workers with and without a chronic health condition

Work ability workers aged 45 years and older

without chronic health condition

with chronic health condition

Ba

Beta

b

95% CI for B

Ba

Beta

b

95% CI for B

Lower

bound

Upper

bound

Lower

bound

Upper

bound


Age (yr)

‐0.015 §

‐0.058

‐0.023

‐0.006

‐0.008

‐0.021

‐0.023

0.007

Gender (referen

ce = m

ale)

0.121§

0.048

0.045

0.198

0.025

0.007

‐0.102

0.152


0.071

0.025

‐0.017

0.160

0.131

0.035

0.010

0.271

Work conditions

Occupation secretary vs executive

‐0.054

‐0.018

‐0.151

0.044

0.294 ¥

0.074

0.135

0.454

Occupation policy vs executive

0.048

0.017

‐0.049

0.145

‐0.034

‐0.008

‐0.207

0.140

Occupation m

anagem

ent vs executive

0.058

0.018

‐0.047

0.163

0.139

0.027

‐0.060

0.337

Work type: physical vs. m

ental job

dem

ands

‐0.097

‐0.019

‐0.259

0.065

‐0.331 *

‐0.052

‐0.581

‐0.080

Work type: both physical and m

ental vs

men

tal job dem

ands

0.017

0.006

‐0.068

0.102

0.029

0.008

‐0.108

0.166


Work attitude

0.005 ¥

0.077

0.003

0.007

0.007 ¥

0.084

0.003

0.010

Coping: active problem focusing

0.035 ¥

0.077

0.021

0.049

0.046 ¥

0.072

0.022

0.070

Coping: avoidance beh

aviour

‐0.033 ¥

‐0.057

‐0.050

‐0.016

‐0.021

‐0.026

‐0.050

0.008

Co‐w

orker support

‐0.013

‐0.021

‐0.030

0.005

0.004

0.005

‐0.025

0.033

Community support

0.029 ¥

0.112

0.019

0.038

0.025 §

0.072

0.009

0.040

Organisational support

‐0.004

‐0.012

‐0.013

0.006

‐0.015 *

‐0.039

‐0.029

‐0.001

76

Table 3:continued

Work ability workers aged 45 years and older

without chronic health condition

with chronic health condition

Ba

Beta

b

95% CI for B

Ba

Beta

b

95% CI for B

Lower

bound

Upper

bound

Lower

bound

Upper

bound



0.006 §

0.053

0.002

0.010

0.008 ¥

0.084

0.004

0.012

Social functioning

0.005 §

0.069

0.002

0.008

0.008 ¥

0.114

0.004

0.012

Role limitations from phy. problems

0.003 ¥

0.075

0.002

0.004

0.005 ¥

0.116

0.003

0.006

Role limitations from emo. problems

0.002 *

0.048

0.000

0.003

0.003 §

0.081

0.001

0.005

Men

tal health

0.006 *

0.057

0.002

0.011

0.005

0.043

‐0.001

0.012

Vitality

0.020 ¥

0.214

0.016

0.023

0.015 ¥

0.139

0.009

0.021

Pain

0.002

0.024

‐0.001

0.005

0.004 *

0.048

0.000

0.007

Gen

eral health

0.005 ¥

0.065

0.003

0.008

0.015 ¥

0.165

0.011

0.019

Total R

‐square (%)

28.7

42.8

n

3395

1852

*p<.05; §p<.01; ¥p<.001, aB, unstandardized

regression coefficient, b beta, standardized

regression coefficient


77

DISCUSSION

The presence of a chronic health condition was related to work ability irrespective of work

conditions and psychosocial factors among workers aged 45 years and older. The

association between the presence of a chronic health condition and work ability,

substantially changed trough the impact of the psychosocial factors. Perceived health

status was very strongly related to the presence of a chronic health condition and

explained its relation with work ability to a great extent. This is not surprising, taken the

fact that subscales of the SF‐36 are multi‐item scales which assess separate aspects of

health and these can better differentiate in health than a single item question. Substantial

differences in variables associated with work ability for workers with and without a

chronic health condition were not found. Psychosocial factors and perceived health status

were most strongly related to work ability for both groups than other variables in our

study. As workers with a chronic health condition reported lower mean scores for work

ability, these workers might have the most benefit by a policy focussing on enhancing

associated variables.

The impact of psychosocial factors on the relation between chronic health conditions and

work ability can be explained by the fact that these psychosocial factors indirectly

influenced both the chronic condition and the work ability. This finding corroborates with

results of previous studies, which found that the strategy to cope with (health) problems

was associated with disability and sickness absence38‐41. Social support has been shown to

be relevant predictors with regard to time to return to work for all types of health

conditions and a more positive attitude towards work was related to a better work ability

level42,43. Support at the work place and in private life were important determinants of

improved work functioning in previous studies17,44,45. One unanticipated finding in this

study was that increased co‐worker support was negatively related to work ability. This

counter‐intuitive result on co‐worker support might be explained by the fact that the

questions about co‐worker support measured expectations and incentives of colleagues

regarding continuing work due to illness. It might be that what we deemed to be co‐

worker support was sometimes perceived as social pressure, which results in a negative

association with work ability. Moreover, the subscale measuring co‐worker support

contained two self‐constructed questions and with unknown content and construct

validity.

The impact of work conditions, as operationalized in this study, was very small. This might

be explained by the particular choice of work‐related factors in our study. Work conditions

varying from role ambiguity, physical climate, work schedule, repetitive movements or

ergonomic conditions have been shown to be predictors of work ability23. The work‐

Chapter 4

78

related factors we used in this study did not focus on characteristics of work, but were

based on work conditions (such as sector, occupation, duration function, and shift work).

Future research should therefore be aimed at examining the influence of work conditions

on the association between the presence of a chronic health condition and work ability.

The variables associated with work ability for workers with and without a chronic health

condition were similar. However, the health variables and psychosocial factors were more

strongly related to work ability for workers suffering from a chronic health condition

compared to workers without a chronic health condition. Moreover, the perceived health

status was lower for workers with a chronic health condition. These findings suggest that

increasing the work ability level for workers suffering from a chronic disease might be

achieved by intervening on psychosocial factors and more importantly on perceived health

status.

To our knowledge, this is the first study to specifically investigate the impact of work

conditions, psychosocial factors and perceived health on the association between the

presence of a chronic health condition and work ability. Although the Work Ability

Questionnaire (WAI) has been used in several studies as the outcome measure to assess

work ability, in this study the first item was used. Whereas the total score of the WAI is

based on the number of chronic health conditions, it is inaccurate to use the WAI to

determine predictors of the association between chronic health conditions and work

ability. Therefore, in this study the single item measure based on the workers’ view of

current work ability compared to when it was at its best is used. A strength of the study is

that it was based on a considerable sample of workers with various occupational activities

(e.g. heavy physical labour, back office, health care, teaching and cleaning) employed in

different companies. The results of the study can therefore be generalized to a large part

of the working population of 45 years and older. Previous studies on the association

between psychosocial factors and work conditions on work ability have conducted in

specific occupational groups3,16,46. Moreover, psychosocial factors in earlier studies were

often actually work‐related such as job demands and lack of control. This study assessed

psychosocial factors based on individual resources like coping behaviour, work attitude,

and perceived support. A limitation of the study was that the cross sectional design does

not permit exploration of causal relationships between the factors on the association

between chronic health condition and work ability. Therefore, it remains unknown

whether, for example, increased co‐worker support was negatively related to work ability

or workers with a low work ability receive more social support from co‐workers.

Nevertheless, the results are still of interest as they provide a first insight into important


79

factors to intervene on regarding work ability among workers aged 45 years and older

with or without a chronic health condition. Additional longitudinal (intervention) studies

are needed to examine causality. A second limitation concerns the fact that self‐report

was used to assess all the variables in this study. As a result, some misclassification of

respondents might have occurred which will most probably have been non‐differential

and thus have resulted in underestimations of the associations under study. However, it is

known from literature that self‐reporting of health status and of certain physical chronic

diseases (diabetes, cardiovascular disease, musculoskeletal and respiratory problems) is

reasonably reliable47. Therefore, we do not expect that the self‐reporting of health and

problems due to ageing introduced any significant bias for this kind of health conditions.

Thirdly, we cannot rule out that non‐response has influenced our results. The overall

response rate of 39% at baseline was regarded to be reasonable for an anonymous survey

in the working population. Because of the anonymous study design, we were not able to

investigate the characteristics of the non‐responders properly. We found that the

response rate in large organisations (> 4000 workers) was lower compared to the smallest

organisations (around 250 workers). Furthermore, we found differences regarding gender

(higher % response of male workers in production and female in health care and

education) and function (more executive workers in production, more policy and

management workers in telecommunication and government). This might be explained

due to sector differences, e.g more male workers in the production compared to health

care and education. Furthermore, the results of our study might not be representative for

workers in the production sector because of the underrepresentation of these workers in

our study. Finally, workers between 45 and 64 years who are still working might be a very

select, relatively healthy group of the general population of this age. This is known as the

healthy worker effect, a phenomenon which is often encountered in occupational

cohorts48,49. In this cohort of older workers the healthy worker selection is probably

stronger than in populations of workers of all ages, because of the many possibilities of

early retirement that were available for older workers in the last two decades. Because of

that the results from our study are probably an underestimation of the influence of

determinants on the association between the presence of a chronic health condition and

work ability.

CONCLUSION AND RECOMMENDATIONS

We found that psychosocial factors and especially perceived health status, rather than

work conditions, explain a large part of the decreased work ability of workers with a

chronic condition. Variables associated with work ability did not substantially differ for

Chapter 4

80

workers with and without a chronic health condition. Based on the lower mean scores for

workers with a chronic health condition for work ability as well for predictors, these

workers might have the most benefit by a policy focussing on enhancing these associated

variables. Given these results, it may be a promising approach to address perceived health

as well as psychosocial factors in strategies and interventions towards a sustainable

healthy working life. Previous studies found beneficial effects of the problem solving

approach on health and work related outcomes50‐52. Problem‐solving based interventions

might increase the workers awareness and behaviour by emphasizing their own decisive

role in attaining goals and giving them the feeling that they can be effective in carrying out

the necessary actions, with support from others. Future research to determine variables

associated with work ability for workers with and without a chronic health condition

should incorporate longitudinal designs and also include work characteristics such as

physical climate, work posture and work demands, as well as job control, decision

authority and work resources.


81

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5

Coping, job control and social support as adaptation

determinants of work ability among ageing workers with and

without a chronic health condition

Submitted for publication

W. Koolhaas

M.R. de Boer

J.W. Groothoff

S. Brouwer

J.J. van der Klink

Chapter 5

86

ABSTRACT

Aim: To examine the association of different coping styles with work ability among

workers aged 45 years and older, and if these association might depend on the extent of

job control and support. Differences in associations between workers with and without a

chronic health condition were examined.

Methods: The data of this cross sectional study were obtained from 5730 workers in five

different sectors. Work ability was assessed with the work ability Index. The Utrecht

coping was used to assess active, emotional and avoidance coping styles. The presence of

a chronic health condition was assessed by self‐report. Multiple regression analysis were

used to examine association, and interaction effect of job control and support.

Results: Active coping is positively associated with work ability, whereas both emotional

and avoidance coping are negatively associated with work ability. No interaction effect of

job control and support were found. For workers with a chronic health condition, the

association between active coping and work ability is stronger, and job control had a small

but positive effect on this association.

Conclusion: An active coping style is the most effective way to adapt to the challenges to

enhance sustainable employability of ageing workers with and without a chronic health

condition.

Key terms: adaptation, ageing workers, chronic health condition, coping, sustainable

employability, work ability

Adaptation determinants of work ability

87

INTRODUCTION

Given the demographic reality of ageing societies in most parts of the world, it has

become essential to realize a sustainable and healthy working life for ageing workers. To

stay in balance with the work demands, most ageing workers have to adapt on several

levels. First, the process of ageing itself has an impact on physical and mental health

status1,2 and is significantly associated with a decreased work ability 3,4. Both health status

and work ability are predictive measures of future disability, sickness absence, future

health, and early discontinuation of working life5‐8. Secondly, ageing is associated with an

increased incidence of chronic health conditions9,10. In 2010 more than one in three

workers in the Dutch working population aged 45 years and older indicated a chronic

health condition2,11 and had to adapt to the consequences of this condition. Finally,

workers have to adapt to the ever faster changing world of work. This is a challenge for all

workers, but ageing workers have a higher probability of getting used to routines in their

working life that may be difficult to change. If ageing workers cannot adapt to these

factors their work ability will be threatened.

Health and work characteristics are important determinants of work ability.

Several studies have shown that these determinants account for only a proportion of the

variation in self‐reported work ability3,12‐14. Determinants associated with adaptation like

coping and conditions which might influence adaptation like job control and social support

may be important for predicting work ability and performance as well. There is some

knowledge about the impact of job control and social support on work ability15,16, but the

above mentioned constructs have not been studied extensively until now in relation to

work ability of ageing workers. Previous studies showed that coping was associated with

several work and work ability related outcomes such as health, job performance17,

stress18, disability18‐20, and job satisfaction21. An active problem‐focused coping style

generally has a positive impact on well‐being and health outcomes20,22,23, results in less

reported absences and fewer critical incidents and errors24, reduces sickness absence

(frequency, length and duration)25, and increased return to work26. Emotion‐focused and

avoidance strategies result in psychological and physical symptoms and an avoiding coping

style is related to both morbidity and multimorbidity27. Therefore, active coping style

seems to be in general the most adaptive and effective style to cope with the demands in

present economies and work organizations.

Job control enables workers to adapt and to cope with work challenges and

demands28. The job demand‐control (JDC) model assumes that job control buffers the

negative effect of job demands on health and well‐being through individual coping29‐31.

High control correlated significantly with high work engagement32, whereas low job

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88

control influences the retirement intention negatively, and strengthened the associations

of poor health and low work ability with retirement intentions6,33. In several studies the

JDC‐model was supported only in subgroups with an (pro)active copings strategy34‐36. This

stresses an interactive affect that active coping and job‐control, as an essential element of

the JDC model, might have. So, the concept of job control might be a second important

factor with respect to adaptation besides an active coping style for ageing workers to

continue their work in good health till reaching retirement age.

Social contextual factors may play a role in the process of adaptation too, as

adaptation is always accomplished in interaction between the individual and his context.

Support of co‐workers and supervisors in the work environment has been found to be an

important factor in this respect37‐39. Like job control, support tends to improve employee

health40 and can buffer the negative effects of job demands41‐43. In addition, social support

from the (work) environment influences the effect of coping strategies in many situations.

The effect of an active coping style on job satisfaction, and thereby on well‐being, has

been shown to be positively associated with the extent of co‐worker and supervisor

support44. Supervisors may be important providers of emotional and instrumental

support45. Therefore, it is plausible that the effect of active coping strategies will be

strengthened by instrumental support. In a similar way the inverse effects of emotion‐

focused and avoidance coping on work ability might be attenuated by emotional support.

As work ability is strongly related to a worker’s self‐rated health and the presence of

chronic health conditions1,46, the association between work ability and coping, and the

interaction effects of job control and social support, might be influenced by the presence

of a health condition. Recent studies indicate that coping related concepts are important

in chronic diseases e.g. chronic kidney disease47, and Parkinson disease48 Workers with a

chronic health condition are often confronted with functional deterioration and physical

disability and coping resources might become essential for managing the work demands49‐

51. Moreover, workplace activity limitations were related to increased reports of all types

of coping for workers with arthritis52.

In summary, the literature suggest a complex interplay between health, factors associated

with adaptation and work ability, but systematic analyses have been scarce. The aim of

the present study is to examine a) the association between coping styles and work ability

among workers aged 45 years and older, b) whether job control and support modify these

associations, and c) whether these associations are similar for workers with and without a

chronic health condition.


89

More specifically, the following five hypotheses are formulated:

1. An active coping style is associated with a higher work ability, and emotion‐

focused and avoidance coping styles are associated with a lower work ability for

ageing workers;

2. The association of active problem‐solving coping with work ability is stronger for

ageing workers with higher levels of job control;

3. The association of active problem‐solving coping with work ability is stronger for

ageing workers with higher levels of instrumental support;

4. The negative association of expression of emotions and avoidance coping with

work ability is weaker for ageing workers with higher levels of emotional support;

5. The associations mentioned in hypotheses 1‐4 are stronger for ageing workers

with a chronic health condition compared to workers without a chronic health

condition.

METHODS

Study population and procedure


and older. Ten companies representing five different sectors (education, health care,

production industry, government and telecom), invited by their occupational health

physicians, agreed to participate in the study. A self‐administered questionnaire,

consisting of 132 items, was sent to all workers aged 45 years and older (N=14,565). All

companies enclosed a letter of recommendation. The voluntary nature of participation

and confidentiality of the information they provided was guaranteed. Four weeks after the

initial mailing, all workers received a written reminder. The data were collected in

February and March 2008.

The Medical Ethics Committee of the University Medical Center Groningen

approved the study design and deemed ethical review unnecessary due to the non‐

medical nature of the research. All participants signed informed consent.

Measures

Work ability was measured by the Work Ability Index (WAI) , a self‐administered

questionnaire comprising seven scales: (i) subjective estimation of current work ability

compared with lifetime best (0–10 points); (ii) subjective work ability in relation to both

physical and mental demands of the work (2–10 points); (iii) number of diagnosed

diseases (1–7 points); (iv) subjective estimation of work impairment due to diseases (1–6

points); (v) sickness absenteeism during the past year (1–5 points); (vi) own prognosis of

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90

work ability after 2 years (1 or 4 of 7 points); and (vii) psychological resources (enjoyment

of daily tasks, activity and life spirit, optimism about the future) (1–4 points)53. The final

WAI score was calculated by summation of all scale scores and can range from 7 to 49

points. Higher scores on the WAI indicate a better work ability. The reliability [54] and

validity [55] of the WAI are acceptable.

The Utrecht Coping List (UCL) was used to assess styles of coping56. This

questionnaire was designed to measure the coping strategies people use in stressful

situations. In this study we used the short version of the original 47‐item Utrecht Coping

List which include a selected number of dimensions and items and consisting of three

scales: (1) active problem‐focusing (five items), (2) expression of emotions (four items),

and (3) avoidance behaviour (four items). The internal consistencies as well as the test‐

retest reliabilities have been shown to be satisfactory56. The internal consistencies found

for active, expression of emotions and avoiding focused coping strategies in this study

were 0.84, 0.70, and 0.71 respectively.

Perceived support was assessed with a self‐constructed scale reflecting a person’s

perception of social support. The 14 items were answered on a five‐point Likert scale

(totally disagree to totally agree). A confirmatory factor analysis fitted an instrument with

two relevant subscales: 1) emotional support (six items), and 2) instrumental support (six

items). Higher scores indicate more support for both scales. The internal consistencies for

emotional, and instrumental support in this study were 0.70, and 0.72 respectively.

Job control was assessed with four questions from the PRODISQ, partly based on

Karasek’s job control demands57,58. The PRODISQ module contains four questions about

the possibilities to organise one’s own work, decision authority, learning new things and

the opportunity for personal development. Each question was rated on a four point scale

ranging from ‘never’ to ‘always’. Higher scores indicated a higher job control (range 4‐16).

Socio‐demographics were also assessed by questionnaire. The level of education

was operationalized as: no or primary education (no), lower vocational education (low),

intermediate secondary/vocational education (middle) or higher vocational education and

university level (high). Occupation was divided into four groups: executive, secretarial,

policy, and management. The five companies represent a variety of sectors, i.e. health

care, education, government, production industry and telecommunication. We defined a

chronic disease as ‘the subjective experience of a long‐term irreversible disease of more

than 3‐month duration’, which is in accordance with many other studies59,60. It was

assessed by asking the respondents the question: ‘Do you currently have a long‐term or

chronic disease of more than 3‐month duration without the prospect of recovery?’

(yes/no).


91

Statistical analysis

Persons with one or more missing values on the WAI items were excluded from the

computation of a WAI total score according to the manual53. We tested whether persons

with missing values on any of the variables included in the analyses differed from the

persons that had complete data using t‐tests (coping variables, support variables, job

control, and age) and chi‐square tests (chronic health condition, gender, education, sector

and occupation). Persons who did not respond at all, were not included in these analyses,

because we did not have any data for these persons. Next, descriptive statistics were

derived by computing means and standard deviations (SD’s) for normally distributed

continuous variables, medians and interquartile ranges (IQR’s) for continuous variables

that were not normally distributed and numbers and percentages for categorical variables.

This was done for the total sample as well as for participants with and without a chronic

health condition separately.

We constructed several linear regression models in line with the hypotheses of

the study. In the first set of analyses, we examined the relation between active coping,

avoidance coping and expression of emotions on the one hand with the WAI on the other

hand. For each of the coping variables we assessed three models: model 1 was

unadjusted; model 2 was adjusted for age and gender; model 3 was additionally adjusted

for level of education, occupation and sector. In addition, we tested for interaction of

instrumental support and job control in the relation between active coping and work

ability, and of emotional support in the relations between avoidance coping and work

ability, and expression of emotions and work ability. This was done by adding interaction

terms to model 2 of the specific analyses. All regression analyses were performed for the

total sample as well as for participants with and without a chronic health condition

separately. An alpha < 0.05 was used to assess statistical significance for all analyses and

all analyses were performed in IBM SPSS statistics 20.0 (IBM Corp. released 2011, Armonk,

NY.)

RESULTS

Of the total response of 5,730 workers, 771 workers were excluded from the analyses

because of incomplete data on the variables used in the study. The final sample comprised

of 4,953 (34%) complete cases of surveys filled in by workers aged 45 years and older.

Those workers with missing values had a significantly lower mean age (‐0.50 years) and

significantly higher mean scores on active coping (0.83 points) and job control (0.68

points). Furthermore, the group of workers with missing values consisted of significantly

higher percentages of women (44% vs 32%), executive workers (60% vs 45%), production

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92

workers (21% vs 2,5%), no/lower educated workers (35% vs 22%), and less workers in

telecommunication (28% vs 51%), compared to those workers included in the study.

Table 1 shows a description of the baseline characteristics for the total sample and for

workers with and without a chronic health condition separately. The mean age of the total

sample was 53.0 years (SD=4.4) and 68% was male. Most workers were highly educated

(44%) and working in an executive function (45%). Half of the workers were working in the

sector telecommunication (50%), followed by working in the sectors education (23%) and

health care (20%). The presence of a chronic health condition was reported by 35.3% of

the workers (n=3,205). The mean work ability score was 39.6 (SD 5.9), with lower mean

scores for workers with a chronic health condition as compared with workers without a

chronic health condition (35.6 vs. 41.8). Mean scores on active coping (14.9, SD 2.6),

emotional coping (8.5, SD 1.9), avoidance coping (8.2, SD 2.0), job control (10.0, SD1.9)

and the instrumental (19.5, SD4.0) and emotional (24.0, SD4.7) support variables were

fairly similar for these two groups of workers.

For the total sample, the associations between the three coping styles and work ability

were all statistically significant and in the expected direction (Table 2). A more active

coping style was associated with a higher work ability (b=0.324; p<.001) and a more

emotional and avoidance coping style were negatively associated with work ability with

respectively b=‐0.243 ( p<.001) and (b=‐0.363; p<.001) (hypothesis 1). The results show no

statistically significant nor relevant interaction effects of support and job control on the

associations of active coping and work ability (hypotheses 2 and 3). There was also no

significant interaction effect of emotional support on the association of expression of

emotions and avoidance coping (hypothesis 4).


93

Table 1: Baseline characteristics total population, workers with and without a chronic health condition Variable Total

(N=4953)

workers with a

chronic health

condition

(N=1748)

Workers without a

chronic health

condition

(N=3205)

Age in years (mean, SD) α 53.0 (4.4) 53.2 (4.3) 52.9 (4.5)

Gender (N, % male)β 3346 (68%) 1106 (63%) 2240 (70%)

Education β

No (N,%) 46 (1%) 20 (1%) 26 (1%)

Low (N,%) 1009 (20%) 423 (24%) 586 (18%)

Middle (N,%) 1718 (35%) 575 (33%) 1143 (35%)

High (N,%) 2180 (44%) 730 (42%) 1450 (46%)

Occupation β

Executive (N,%) 2231 (45%) 845 (48%) 1386 (43%)

Secretarial (N,%) 1018 (21%) 387 (22%) 631 (20%)

Policy (N,%) 988 (20%) 308 (18%) 680 (21%)

Management (N,%) 716 (14%) 208 (12%) 508 (16%)

Sector β

Production (N,%) 122 (3%) 50 (3%) 72 (3%)

Education (N,%) 1128 (23%) 416 (24%) 712 (22%)

Health care (N,%) 1002 (20%) 378 (22%) 624 (20%)

Government (N,%) 197 (4%) 63 (4%) 134 (4%)

Telecommunication (N,%) 2504 (50%) 841 (47%) 1663 (51%)

Work ability

Work ability (Mean, SD) α 39.6 (5.9) 35.6 (6.3) 41.8 (4.4)

Coping

Active (Mean, SD)α α 14.9 (2.6) 14.8 (2.5) 14.9 (2.5)

Emotional (Mean, SD) α 8.5 (1.9) 8.6 (2.0) 8.4 (1.8)

Avoidance (Mean, SD) α 8.2 (2.0) 8.4 (2.0) 8.1 (2.0)

Job control (Mean, SD) α 10.0 (1.9) 9.7 (1.9) 10.1 (1.9)

Support

Instrumental (Mean, SD) 19.5 (4.0) 19.3 (4.3) 19.6 (3.8)

Emotional (Mean, SD) α 24.0 (4.7) 23.4 (4.8) 24.3 (4.6)

α T‐test statistics shows significant differences (≤.001) between workers with and without a chronic

health condition, α α significant differences (≤.05), β Chi‐square statistics shows significant differences

(≤.05) between workers with and without a chronic health condition

94

Table 2: A

ssociation between coping styles and work ability for workers with and without a chronic health condition

Variable

Total (N=4953)

Workers with a chronic health

condition (N=1748)

Workers without a chronic

health condition (N=3205)

B

95% CI

B95% CI

B95% CI

Active coping model 1∞

0.441*

0.377‐ 0.505

0.513*

0.401‐ 0.625

0.349*

0.290‐ 0.409

Active coping model 2^

0.431*

0.367‐ 0.495

0.513*

0.401‐ 0.624

0.343*

0.284‐ 0.402

Active coping model 3

$0.324*

0.259‐ 0.390

0.424*

0.310‐ 0.537

0.268*

0.207‐ 0.330

Interaction with job control

0.016

‐0.014‐ 0.046

0.068**

0.016‐ 0.121

‐0.005

‐0.033‐ 0.024

Interaction with instrumental support

‐0.007

‐0.021‐ 0.008

0.009

‐0.015‐ 0.032

‐0.008

‐0.022‐ 0.006

Expression of em

otions model 1∞

‐0.179*

‐0.266‐ ‐0.091

‐0.078

‐0.224‐ 0.067

‐0.122**

‐0.207‐‐0.038

Expression of em

otions model 2^

‐0.176*

‐0.264‐ ‐0.087

‐0.086

‐0.233‐ 0.061

‐0.136**

‐0.222‐‐0.051

Expression of em

otions model 3

$‐0.243*

‐0.330‐ ‐0.156

‐0.138

‐0.282‐ 0.007

‐0.198*

‐0.282‐‐0.114

Interaction with emotional support

‐0.004

‐0.022‐ 0.013

‐0.011

‐0.039‐ 0.017

‐0.003

‐0.020‐ 0.014

Avoidance coping model 1∞

‐0.369*

‐0.450‐ ‐0.288

‐0.289*

‐0.434‐‐0.145

‐0.273*

‐0.348‐‐0.198

Avoidance coping model 2^

‐0.369*

‐0.450‐ ‐0.288

‐0.302*

‐0.446‐‐0.157

‐0.279*

‐0.354‐‐0.204

Avoidance coping model 3

$‐0.363*

‐0.443‐ ‐0.283

‐0.293*

‐0.437‐‐0.150

‐0.270*

‐0.344‐‐0.196

Interaction with emotional support

0.015

0.000‐ 0.031

0.001

‐0.026‐ 0.028

0.018**

0.003‐ 0.034

∞Model 1: u

nadjusted

^Model 2: adjusted

for age and gender

$Model 3: adjusted

for level of ed

ucation, occupation and sector

*p≤.001, **p

≤0.05


95

When examining the relations for the two subgroups of ageing workers with and without a

chronic health condition separately (hypothesis 5), we found significant associations

between active and avoidance coping and work ability for both groups. For workers with a

chronic health condition, the association between active coping and the WAI were

stronger (b=0.424 versus b=0.268), whereas the associations between avoidance coping

and work ability were of similar magnitude (b=‐0.293 versus ‐0.270) compared with those

workers without a chronic health condition. For workers without a chronic health

condition expression of emotions has a negative impact on the association with work

ability (b=‐0.198). This negative impact was weaker (b=‐0.138) and not statistically

significant for workers with a chronic health condition.

Two statistically significant interaction effects were found. For ageing workers with a

chronic health condition the association between active coping and work ability was

modified by job control (b=0.068; p=0.011). This means that for workers with a five point

higher score on job control the regression coefficient for the relation between active

coping and work ability was 0.34 points higher. For ageing workers without a chronic

health condition, emotional support showed a positive interaction on the association

between avoidance coping and work ability (b=0.018; p=0.018), meaning that this relation

was weaker (less negative) for persons with higher scores on emotional support.

DISCUSSION

The results of our study confirm hypotheses 1 and 5. The relations between the three

coping styles and work ability were all statistically significant. An active coping style was

associated with a higher work ability, whereas expression of emotions and avoidance

coping were negatively associated with work ability (hypothesis 1). Contrary to our

hypotheses (2,3 and 4), no interaction effects of instrumental support and job control

were found. When examining the relations for ageing workers with and without a chronic

health condition separately, we found stronger associations between active coping and

work ability for ageing persons with a chronic health condition than for persons without

such a condition (hypothesis 5). The association between the coping style expression of

emotions and work ability was stronger for workers without a chronic health condition.

Job control strengthened the association between active coping and work ability for

workers with a chronic health condition, whereas emotional support buffered the

association between avoidance coping and work ability for workers without a chronic

health condition.

These findings indicate that in today's society, with its dominance for self‐

direction and its tendency to reframe problems as challenges, the active coping style is the

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96

most effective in the majority of situations for workers aged 45 years and older. As most

work situations are complex in present days economies this could be strengthened by the

fact that in ambiguous situations, a focus on one strategy might be more effective61.

In contrast to our second hypothesis, the association of active problem‐solving

coping with work ability was not strengthened by job control in ageing workers. These

results suggest that the relationship between active coping and work ability do not

become stronger with higher job control. We expected that job control as organizational

resource would enable ageing workers to cope in an active way. The job demand control

model of Karasek posits that control buffers the unhealthy effects of job demands on

health and well‐being and predicts that jobs combining high demands and high control

enhance opportunities for active coping strategies29. These null‐findings are in line with

previous studies by Shimazu (2004, 2005) in which job control did not change or buffer the

(negative) relation between active coping and outcomes like psychological distress or job

satisfaction44,45. A possible explanation might be that the level of controllability (mean

score job control of 10 on a range from 4 to 16) for the workers included in our study was

in balance with the needs and demands in the participating work organisations with as

consequence that we did not find the hypothesized interaction

Another finding was that we did not find the hypothesized interaction effect for

instrumental or emotional support on the relation between coping styles and work ability

for the total group. Based on the extended model of Karasek, it was expected that social

support would buffer the negative effect of job demands on health and well‐being, and

thereby work ability, through individual coping42,62,63. A review study on this model

reported that additive effects of social support on general psychological well‐being are

almost always found if the sample size is sufficient64. From previous studies it is also

known that supervisor support is an important predictor of work ability, especially for

workers with a chronic health condition15,65,66. In the present study we found no evidence

that this relation can be explained by facilitating active coping.

Distinguishing between ageing workers with and without a chronic health condition shows

that the relation between an active coping style and work ability is stronger for people

with a chronic health condition. The results of this study are consistent with previous

studies. These studies showed that persons with moderate to high impairment of physical

function and emotional well‐being reported more frequent use of active coping

strategies67 and that longer illness duration of patients with chronic fatigue syndrome

resulted in a higher use of an active coping approach68. This might be explained by the fact

that their health condition provides an extra (partly) controllable challenge to adapt to the


97

work demands. A strong focus on the active coping style might almost be a prerequisite to

enhance their ability in controllable situations. The fact that expression of emotions has a

less negative effect for these workers with a chronic health condition might reflect that

their condition confronts them with incontrollable situations too, for which an expression

of emotions style might be adaptive61,69,70.

For workers with a chronic health condition we found that experienced job

control had a small but positive effect on the association between active coping and work

ability. Control over ones time scheme or the sequence in which tasks are performed, may

contribute to a successful adaptation to limitations as a consequence of the health

condition71,72. For workers without a chronic health condition, we found emotional

support to buffer the negative effect of an avoidance coping strategy. This is in accordance

with our hypothesis for the total group, but the effect is small.

To our knowledge, this is the first study to specially investigate determinants associated

with adaptation to enhance work ability. A strength of our study is that the results are

based on a considerable sample of workers with various job characteristics (e.g. job

demands and job control) employed in different companies. The results of the study can

therefore be generalized to a large part of the working population of 45 years and older. A

limitation of the study was that the current study is cross‐sectional in nature. This design

does not permit exploration of causal relationships between coping and work ability.

Nevertheless, the results are still of interest as they provide a first insight into the

determinants associated with adaptation for ageing workers with and without a chronic

health condition to enhance sustainable employability. Our design also automatically

meant that we used data from workers still working, who may present a select, relatively

healthy group of the general population of this age. Because of this selection, the data

from this study probably presents underestimations of the scores on all work related

outcomes in the entire group73,74. It is unclear whether and how this might have

influenced our results related to the postulated hypotheses, but bias might have occurred

in any direction. Second, the overall response rate of 39% at baseline is regarded to be

reasonable for an anonymous survey in the working population, but results related to

selective participation cannot be ruled out. Because of the anonymous study design, we

were not able to investigate the characteristics of the non‐responders properly.

Nevertheless, we believe there is no reason to expect that workers with ageing problems,

lower work ability or a chronic health condition returned the questionnaire less frequently

than workers without problems. The questionnaire addressed a variety of themes, and did

not emphasize functional ageing, chronic health condition or the outcomes work ability

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and coping. A third issue concerns the self‐reporting nature of the study because the

perception of workers’ responses could not be externally validated. As a result, some bias

may exist in the classification of respondents on the basis of self‐reported data, resulting

in an underestimation of the differences and associations under study. Finally, the current

study does not distinguish between specific chronic health conditions because of the lack

of knowledge of the severity and limitations of the conditions. It is possible that severely ill

and chronically disabled are in most cases excluded from working life and their

perspectives are not included in our sample.

In conclusion, this study indicates that in today's society with its dominance for self‐

direction and its tendency to reframe problems as challenges, the active coping style is the

most effective in the majority of situations for workers aged 45 years and older. This

seems especially true for workers with a chronic health condition. These workers can be

further supported in their adaptation by enhancing their job control.

On the individual level the adaptation of ageing workers can be strengthened by

stimulating them in adopting an active coping style. Interventions aimed at increasing the

awareness of workers of their responsibility and the possibilities they have to be actively

engaged in coping with work problems might enhance a sustainable working life.


99

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1999;49:225‐229.

6

Enhancing a sustainable healthy working life:

design of a clustered randomized controlled trial

BMC Public Health. 2010 Aug 6;10:461

W. Koolhaas

S. Brouwer

J.W. Groothoff

J.J. van der Klink

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ABSTRACT

Background: To improve a sustainable healthy working life, we have developed the

intervention ‘Staying healthy at work’, which endeavours to enhance work participation of

employees aged 45 years and older by increasing their problem‐solving capacity and

stimulating their awareness of their role and responsibility towards a healthy working life.

This research study aims to evaluate the process and the effectiveness of the intervention

compared with care as usual.

Methods/design: The study is a cluster‐randomized controlled trial design (randomized at

the supervisor level), with a 1‐year follow‐up. Workers aged 45 years and older have been

enrolled in the study. Workers in the intervention group are receiving the intervention

‘Staying healthy at work’. The main focus of the intervention is to promote a healthy

working life of ageing workers by: (1) changing workers awareness and behaviour, by

emphasizing their own decisive role in attaining goals; (2) improving the supervisors’

ability to support workers in taking the necessary action, by means of enhancing

knowledge and competence; and (3) enhancing the use of the human resource

professionals and the occupational health tools available within the organization. The

supervisors in the intervention group have been trained how to present themselves as a

source of support for the worker. Workers in the control group are receiving care as usual;

supervisors in the control group have not participated in the training. Measurements have

been taken at baseline and will be followed up at 3, 6 and 12 months. The primary

outcome measures are vitality, work ability and productivity. The secondary outcomes

measures include fatigue, job strain, work attitude, self‐efficacy and work engagement. A

process evaluation will be conducted at both the supervisor and the worker levels, and

satisfaction with the content of the intervention will be assessed.

Discussion: The intervention ‘Staying healthy at work’ has the potential to provide

evidence‐based knowledge of an innovative method to promote a sustainable healthy

working life in the older working population. The results of the study will be relevant for

workers, employers, occupational health professionals and human resource professionals.

Trial registration: The trial is registered with the Dutch Trial Register under number

NTR2270.


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BACKGROUND

Ageing of the workforce exerts pressure on society with respect to health, wealth and

social insurance systems, which are inextricably linked1. Older workers are more

vulnerable in the labour process, because of vitality and ageing problems affecting their

daily performance and their ability to meet job competence requirements2‐6. Ageing is

associated with a higher sickness absenteeism rate7, reduced work ability and decreased

productivity8‐10. Most societies are geared to retirement at around 65 years of age. An

inability to meet work demands, due to ageing, forces older workers to leave the labour

market before reaching retirement age11,12. In addition, the age of the working population

is declining13. This situation affects government budgets and social securities, and puts

pressure on the current arrangements for public pensions and healthcare11,12.

The nature of work has changed over recent years due to globalization and

information technologies (the ‘new economy’) in the Organisation for Economic Co‐

operation and Development (OECD) countries, and work‐based life‐long learning is

required14. Moreover, the more dynamic market and shorter product cycles have resulted

in fewer jobs, with frequent job changes over a working lifetime14. To keep workers in the

labour market during the coming decades, employers should invest in education for and

training of their employees, and the implementation of policies and working methods to

enable workers to have the necessary competencies for longer working lives12,15. Due to

these changes in the labour market, the employee–employer relationship has evolved

from one of mutual loyalty to one based on personal gain. Workers are increasingly

responsible for their own career, and they need to be aware of their own responsibility

and decisive role in creating and/or maintaining a healthy work life. Most intervention

studies to promote workers’ health to extend working life, provide a lifestyle training

programme, for a specific group of workers, to improve job retention16, increase vitality17

or decrease work disability and sickness absenteeism18‐21. However, to gear the work

demands and activities to the personal capabilities of the worker, in order to maintain and

promote sustainable work participation, a strategy for older workers to solve problems

with regard to ageing and chronic health conditions is required, involving good

cooperation between the supervisor and the employee22‐24. We have therefore developed

an intervention to improve a healthy sustainable working life for workers aged 45 years

and older.

Our intervention is called ‘Staying healthy at work’. The goal of the intervention is to

promote a healthy sustainable working life of older workers until retirement age by: (1)

changing workers awareness and behaviour by emphasizing their own decisive role in

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108

attaining goals and giving them the feeling that they can be effective in carrying out the

necessary actions; (2) improving supervisors’ ability to support workers in taking the

necessary actions by means of enhancing knowledge and competencies; and (3)

enhancing the use of human resource professionals (HRPs) and occupational health tools

available within the organization.

The rationale of the intervention is based on theoretical models and theories, on

the results of a survey study of workers aged 45 years and older and on four expert

meetings. A detailed description of the development of the intervention is presented in

the Appendix (additional file 1). The primary aim of this intervention study is to evaluate

the effectiveness of the ‘Staying healthy at work’ intervention compared with care as

usual (CAU) on productivity, vitality and work ability. We hypothesized that after

undergoing the intervention, older workers would improve sustainable work participation

by using problem‐solving strategies with regard to health problems or opportunities to

create a healthy work situation compared with workers who received CAU. The secondary

aims are to improve work attitude, self‐efficacy and work engagement, and to decrease

fatigue and job strain. A process evaluation will be conducted among workers and

supervisors. To our knowledge, this is the first study focusing on a sustainable healthy

working life.

METHODS/DESIGN

The methods and design of the intervention study are as described in the CONSORT

statement and the extension for cluster‐randomized trials25,26.

The study is designed as a two‐armed cluster‐randomized controlled trial (RCT) with a 1‐

year follow‐up. In the study, the intervention group will be compared with CAU (Figure 1).

Eligible workers could not be randomly assigned to supervisors in the intervention group

or supervisors randomly assigned to eligible workers in the control group, because the

supervisor and worker are bound to each other by their department. Moreover, training

all supervisors before randomization was not possible because of the risk of data

contamination. Therefore, cluster randomization was applied at the supervisor level27.

Supervisors at the same department have been placed in either the intervention or the

control group. Workers with their supervisor in the intervention group have been

allocated to the intervention group, and workers with their supervisor in the control group

have been allocated to the control group.

The Medical Ethical Board of the University Medical Center of Groningen

informally approved the study design. They decided that this study did not need an ethical


109

approval, because this study did not perform clinical research with medicinal product for

human beings according to the Dutch law. Workers could participate voluntarily in this

study, and they are free to leave the study at any time without further consequence. All

workers signed an informed consent to participate in the study.

Study population

Recruitment of participants took place at the University and the University Medical Center

of Groningen. The source population consisted of workers aged 45 years and older from

different departments: intensive care, administration, personnel and executive workers.

Workers on long‐term sick leave with no prospect of recovery, or workers who left the job

within 1 year because of illness or pension have been excluded from the study.

Recruitment of the supervisors

Supervisors at the departments proposed by the HRPs were invited to participate in the

study. Supervisors who were interested in the intervention method and were willing to

participate in the study received information about the procedure.

Procedure

The supervisor informed the workers of the upcoming intervention. Hereafter, the

workers received a letter of invitation to participate in the study, describing the aim,

content and set‐up of the study. Workers were invited to return a signed informed

consent to confirm their participation. Workers who were willing to participate in the

study received a baseline questionnaire (paper version) and a postage‐paid envelope.

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110

Figure 1: Study design. Overview of the study design of the intervention

Recruitment of the supervisors

Supervisors randomly allocated to the

intervention or the control group

Training of supervisors No training of supervisors

Informed consent and baseline

questionnaire

Informed consent and baseline

questionnaire

Recruitment of workers by the

supervisors

Recruitment of workers by the

supervisors

Care as usual Intervention

Follow‐up questionnaire

at 3, 6, and 12 months

Follow‐up questionnaire

at 3, 6, and 12 months


111

Intervention

Supervisor training in the intervention group

The supervisors received training before the implementation of the intervention, which

consisted of two components. The first training of 2 hours focused on knowledge

regarding a sustainable healthy working life, and on problem‐solving techniques. After 2

weeks, the second training took place, which consisted of an active training module in

which the problem‐solving techniques were taught, and practiced by role play. In this 5‐

hour training module, the trainer was assisted by an actor. The supervisors were trained in

skills to support the worker in basic problem‐solving techniques. A structured method for

identifying problems, solutions and applications of the solutions was offered, and skills to

guide the worker in using this method were taught. Moreover, the supervisor was trained

on how to present him‐ or herself as a source of support for the worker; not by taking

over responsibilities, but by strengthening the autonomy of the worker. Furthermore, the

supervisors received an overview of HRP and occupational health tools available within

the organization, such as work adjustments, training and education. This should help them

to advise their workers about which tools they could use to optimize work capacities and

personal development, and thereby work participation.

Intervention for workers in the intervention group

Step 1: inventory of problems, solutions and degree of changeability

Workers in the intervention group received a booklet. The content of the booklet was

based on the problem‐solving strategy described by Fontana28 and modified by van der

Klink29,30. The booklet is designed by the researchers to help with clarifying and exploring

problems with work functioning, working career and support needs, and stimulate

workers to think about possible solutions. In the booklet, examples of problems at work

due to ageing and support needs, possible solutions, and their role and responsibility in

creating a sustainable working career are described. The workers made an inventory of

experienced problems, barriers and support needs, including concrete examples of work

situations in which these problems occur. In addition, workers could indicate career

aspirations. Hereafter, workers determined the degree of changeability of each described

point. Workers needed to consider which changes they could realize by themselves, either

by changing the situation or by mobilizing support (e.g. supervisor, occupational physician,

social worker or psychologist), or, when the situation could not be influenced, by learning

how to cope with it, and accepting it. The booklet was sent to the supervisor after

finishing these first steps.

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Step 2: dialogue between worker and supervisor

The worker’s inventory in the booklet was the input for the dialogue between worker and

supervisor. The dialogue took place within 3 months of sending the booklet to the

workers. During the dialogue, the supervisor helped to establish the worker’s experienced

problems in work functioning, goals and solutions, on the process level. After identifying

problems with work functioning, support needs and defining career opportunities, a

concept action plan was made after brainstorming about the possibilities, actions and

responsibilities of both the worker and his supervisor.

Step 3: Action plan

After the dialogue with the supervisor, the worker made an action plan for the next 1‐year

follow‐up period. The booklet that workers received before the dialogue contained an

example of an action plan format to help workers to create their own action plan. Within 2

weeks of the dialogue, the worker had to complete this action plan, including the solutions

discussed with the supervisor. Workers are responsible for the execution of these actions

during the following year – when necessary, with the support of the supervisor or other

professionals. After 1 year, during the next annual assessment between worker and

supervisor, the action plan will be evaluated and both results and process will be

discussed.

Treatment of the control group

The supervisors in the control group did not receive training. If the intervention ‘Staying

healthy at work’ proves to be effective, the supervisors in the control group will be trained

in the future. Workers in the control group are being given CAU, which implies no

structured support, but the possibility of counselling or support by HRPs or other

professionals as required, or participating in training and human resource tools.

EFFECT EVALUATION

To investigate the effectiveness of the intervention ‘Staying healthy at work’, all workers

received a baseline questionnaire, and follow‐up questionnaires are to be filled in at 3, 6

and 12 months.

Socio‐demographic variables

At baseline, socio‐demographic data (gender, age, level of education, nature of work,

current work status, working hours a week) have been collected.


113

Primary outcome

The primary outcomes of the study are: work ability, vitality and productivity.

Work ability

Work ability is being measured by the Work Ability Index (WAI)31, a self‐administered

questionnaire comprising seven scales: (1) subjective estimation of current work ability

compared with lifetime best (0–100 points); (2) subjective work ability in relation to both

physical and mental demands of the work (2–10 points); (3) number of diagnosed diseases

(1–7 points); (4) subjective estimation of work impairment due to diseases (1–6 points);

(5) sickness absenteeism during the past year (1–5 points); (6) own prognosis of work

ability after 2 years (1 or 4 of 7 points); and (7) psychological resources (enjoyment of daily

tasks, activity and life spirit, optimism about the future) (1–4 points). The final WAI score

is calculated by summation of all scale scores and can range from 7 to 49 points. The

reliability and validity of the WAI are acceptable32,33. Higher scores on the WAI indicate a

better work ability. Based on this WAI score, the individual’s work ability can be classified

into four categories: poor (7–27 points); moderate (28–36 points); good (37–43 points);

and excellent (44–49 points).

Vitality

Improvements in health‐related outcomes are being evaluated with the self‐reported 12‐

Item Short Form Health Survey (SF‐12), an abbreviated version of the 36‐Item Short Form

Health Survey34‐36. The SF‐12 provides two summary scores, the Physical Component

Summary (PCS) score, which represents what a person can do, and the Mental Component

Summary (MCS) score, which represents how a person feels. The mean PCS and MCS of

the general population are 50, with a standard deviation of 10. A higher score means a

better quality of life.

Productivity

Productivity is being measured with the QQ method, which aims at measuring the

quantity and quality of work performed on a daily basis37. The workers indicate how much

work they actually perform during regular hours on their last regular work day during a

working week as compared with a normal week day. The quantity of productivity is

measured on a 10‐point rating scale with 0 representing ‘nothing’ and 10 representing

‘normal quantity’. Meerdings et al.9 showed that self‐reported productivity in the QQ

measurement correlated significantly with objective work output.

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Secondary outcome

The secondary outcomes of the study are changes in fatigue, psychosocial work

characteristics, work attitude, self‐efficacy and work engagement.

Fatigue

To determine the level of fatigue, we are using the Checklist Individual Strength (CIS) [38].

The CIS is a 20‐item well‐evaluated questionnaire for the working population, measuring

four aspects of fatigue in separate scales. In this study, the subscale of the subjective

feeling of fatigue (eight items) is being used. The items are scored on 7‐point Likert scales

ranging from ‘Yes, that is true’ to ‘No, that is not true’. Higher scores on the separate

scales indicate higher degrees of fatigue38.

Psychosocial work characteristics

The Job Content Questionnaire (JCQ) is a self‐administrated questionnaire designed to

measure job strain39. The domains assessed are job demands (5 items), decision authority

(3 items), skill discretion (6 items), social support from supervisors (4 items) and co‐worker

support (4 items). Each domain is rated on a 4‐point scale from ‘strongly disagree’ (most

negative) to ‘strongly agree’ (most positive). The reliability of the scales is good40.

Work attitude

Perceived work attitude is being measured with a Dutch language version of the Work

Involvement Scale (WIS‐DLV), reflecting the degree to which a person wants to be

engaged in work41. The questionnaire consists of six items; with responses on a 1–4 point

scale (strongly disagree, disagree, agree, strongly agree). Higher scores on the WIS‐DLV

indicate more positive attitude towards work.


115

Self‐efficacy

Self‐efficacy is being measured with the standardized Dutch version of the General Self‐

Efficacy Scale42, assessing the subjects’ expectations of their general capacities43. This 16‐

item questionnaire incorporates three subscales: willingness to exert effort in completing

the behaviour, persistence in the face of adversity, and willingness to initiate behaviour. It

consists of five response items (ranging from disagree to agree); higher scores indicate a

higher self‐efficacy.

Work engagement

Work engagement is being measured by a short Dutch version of the Utrecht Work

Engagement Scale (UWES‐9), which enquires how often the respondents currently

experience positive emotions at work44. The UWES‐9 consists of nine items rated on a 7‐

point scale ranging from ‘never’ (0) to ‘always/every day’ (6). The items are divided into

the subscales vigour, dedication and absorption. A total score is obtained by averaging the

individual item scores (possible range 0–6). The internal reliability and validity of the

Dutch UWES‐9 are acceptable45.

Process evaluation

The process evaluation will examine the applicability to implement the intervention

‘Staying healthy at work’ at both the supervisor and the worker level. The supervisors in

the intervention group received a questionnaire before and will receive one after the

training to examine the quality of the training, the content of the training, and the added

value of the training, as a strategy to improve the communication with the workers

regarding work participation and work functioning.

Among the workers of the intervention group, experiences with the use of the

intervention will be evaluated in the follow‐up questionnaires. Workers were asked to

evaluate the content and the relevance of the information leaflets and the booklet to

prepare for the dialogue. Also the dialogue with the supervisor will be evaluated in the

questionnaire after 3 months. All follow‐up questionnaires contain items about the

support of the supervisor, the contribution of the booklet to help make an inventory and

action plan, and the workers’ experiences with the problem‐solving strategy to stimulate

communication about work performance. In addition, questions will be asked about the

enhanced problem‐solving capacity and awareness with regard to the workers’ own role

and responsibility towards a healthy and motivating work situation. Workers will also be

asked to evaluate whether the work‐related situations they wanted to improve have

actually improved, whether they had used HR tools, training, education or contacted

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professionals during the intervention and if they had attained the goal they had in mind at

the start of the intervention. Both workers and supervisors received questions at the

baseline and will receive follow‐up questionnaires about the readiness for change

concerning the intervention.

Reasons for complying or not complying will be asked in the follow‐up workers’

questionnaire as well, in order to gain insight into the potential success of

implementation.


All analyses will be performed according to the intention‐to‐treat principle. Baseline

characteristics of workers will be analyzed for differences between the intervention and

the control groups. Differences between the intervention and the control groups in

changes on the outcome variables will be performed with multi‐level longitudinal analysis.

Intra‐cluster correlations will be determined for all primary outcome variables. Effects of

the intervention will be controlled with covariates, such as gender and job type. Further

analyses will include the comparison of the secondary outcomes at follow‐up between the

two arms. For all analyses a two‐tailed significance level of p<0.05 is considered to be

statistically significant. All analyses will be carried out with the statistical package SPSS

version 16.0 (SPSS Inc. Chicago, IL, USA).

Power calculations and sample size

Work ability, measured with the Work Ability Index (WAI) [46] is the primary

outcome measure for the power calculation. The range of the summative index of the WAI

is 7–49, which is classified into four subgroups: poor (7–27), moderate (28–36), good (37–

43), and excellent (44–49)31. The target of this intervention study is to increase the mean

scores of the workers to those of the next subgroup. This implies a minimum increase of

5.4 (24%) for workers with a poor work ability, and minimum increase of 3.7 (11% and 9%,

respectively) for workers with a moderate and good work ability before the intervention.

For the workers with an excellent WAI score at baseline, the aim is to maintain the score.

The survey study demonstrates that the effect size of workers is high (≥0.80).

We used Optimal Design47,48 to calculate the optimal sample size by a power of

0.80 for testing the treatment effect in this cluster‐randomized trial with an intervention

and a control group in a repeated measurement design. A literature search on the role of

the supervisor to the worker’s attitude24,49 showed an intra‐class correlation (ICC)

between 0.11 and 0.26 for supervisors. We used the most extreme value (ICC = 0.26) for

the power calculation. A total of 20 supervisors are enough to reach a power of 80%.


117

Calculating from 80% power (two‐sided, alpha = 0.05, 20 supervisors) a sample

size of eight workers per supervisor are needed to determine a significant difference

between the intervention and the control groups. The eight workers must be viewed as

the average number of workers per supervisor. This requires at least 80 workers in each

group. Allowing for a loss to follow‐up of 15%, a sample size of 92 workers (in each group)

is required.

Blinding

The validity of the study will be compromised if information is known about the

intervention in the control group. To minimize data contamination, pre‐randomization at

the supervisor level is applied for allocating the workers into the intervention or the

control group. Therefore, different information about the study can be provided to

workers in the intervention and the control groups27. Workers in the control group do not

know the content and design of the intervention ‘Staying healthy at work’. Whereas

workers in the control group are blinded to the intervention, blinding of the supervisors

was not possible. Supervisors in the control and the intervention groups have been

informed about the content of the intervention, because they already knew the set‐up of

the study prior to their decision to participate.

DISCUSSION

The results of this cluster‐randomized controlled study will provide input for an evidence‐

based intervention which may improve a sustainable healthy working life of workers aged

45 years and older. The intervention offers a structured method for workers to

communicate with their supervisor about their work environment, barriers to work

performance and career opportunities. Aspects concerning intervention procedure are

described in the protocol; however, supervisors and workers are free to choose specific

tools at each phase of the process. We assume that such a structured (non‐protocol)

intervention strategy giving workers the opportunity to make an action plan for the next

1‐year follow‐up period, will be an effective way to create a sustainable, healthy, working

life for older workers. Moreover, this method has been shown to be effective in

shortening sick‐leave duration by workers on their first sick leave50.

Strengths

One of the main strengths of the intervention ‘Staying healthy at work’ is that it offers a

strategy to improve the problem‐solving capacity of both workers and supervisors. The

workers will be trained to be aware of their own decisive role in attaining goals, and they

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will learn how to cope with future problems related to work participation. The skills of the

supervisors will be improved by strengthening the workers’ ability to act and make

decisions autonomously, and to not take over the workers’ responsibilities. Additional

value of the intervention is that the method will contribute to the annual assessment,

between supervisor and worker, of work functioning and participation. The intervention

method can be incorporated into the annual worker assessments within the organization.

Another strength of the intervention is the close cooperation with the HRPs during the

development of the intervention. This offers a tool and a process that fit in with the

existing company policy and improves the likelihood of effectiveness of the intervention.

Furthermore, the intervention will contribute to the knowledge and the use of the current

tools, education and training within the organization to enhance work participation.

Although many organizations have these tools available in their current policy, supervisors

and workers are often unaware of the opportunities they have aimed at improving the

working environment. The fact that the perspectives of the workers on work functioning

will be taken into account is also a strength of this study. We presume that this will lead to

a better compliance of the workers to participate actively in the intervention programme.

This will improve the effectiveness of the study. Finally, the cluster design of the study

reduces the risk of data contamination between workers in the intervention and the

control groups. Supervisors are randomly assigned to the intervention or the control

group. Pre‐randomization enables workers in the intervention group to be informed

separately, and therefore makes it possible to blind the workers in the control group to

the study condition.

Weaknesses

The variations between the supervisors is a drawback of the design. Supervisors in the

intervention group are trained to apply the problem‐solving capacity strategy and to

present themselves as a source of support to the workers. Variation between supervisors,

such as differences in knowledge, capabilities, experience with communication,

personality and readiness for change, can influence the results of this study, because of

the decisive role of the supervisor during the dialogue between worker and supervisor.

The process evaluation of the current study will give insight into the role of the supervisor

during the dialogue and the follow‐up of the study. Furthermore, a longer follow‐up than

the 12 months, as planned in the design, is preferable to investigate longer term

intervention effects on a sustainable healthy working life. Workers make an action plan for

the coming year based on one or two points of the inventory of problems, support needs

and working career in the booklet. One year later, during the next dialogue between


119

worker and supervisor, the actions will be evaluated and both results and the process will

be discussed. In addition, they make an agreement about the next action to optimize work

performance. Therefore, it would be advisable to follow the workers for more than 12

months. Another limitation of our study is that the evaluation of effect consists of

measuring enhanced work ability, vitality and productivity. Moreover, no economical cost‐

effectiveness evaluations are included.

Relevance of the study

To pro‐actively address the issue of a shifting workforce composition, companies must

anticipate and identify workforce issues within their organizations, and also develop

strategies to effectively mitigate any workforce‐related risks. A healthy working life

requires close attention being paid to each workers’ life‐cycle phase (learning, applying,

providing and diminishing) and individual demographic characteristics, such as age and

health. A policy to provide a diverse, challenging and balanced working life is needed to

increase knowledge, motivation and thereby participation. This study is focusing on

enhancing the problem‐solving capacity of workers to enhance work participation. The

intervention ‘Staying healthy at work’ is not only designed to enhance work participation,

but also to enhance the workers’ resources and capabilities to continue working in good

health until retirement.

Abbreviations HRP(s) = human recourse (management), CAU = care as usual, WAI = work ability index, PCS =

physical component summary, MCS = mental component summary, QQ = quantity and quality, CIS =

checklist individual strength, JCQ = job content questionnaire, WIS = work involvement scale, UWES

= Utrecht work engagement scale, ICC = intraclass correlation.

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ADDITIONAL FILE 1

Development of the intervention; Specification of the development of the intervention.

To determine the content of the intervention, the following steps were taken: literature

search, survey study and consultant meetings. Based on this information, we defined the

three objectives of the intervention.

Literature search

The rationale of the intervention is based on a number of theories and models: problem‐

solving, empowerment and behavioural change models.

The problem‐solving strategy is described in the guideline ‘Management of mental health

problems of workers by occupational physicians’ of the Netherlands Society of

Occupational Medicine29,30. The goal of the guideline is to support workers to control their

own functioning in the work situation. A structured strategy for identifying problems,

solutions and applications of solutions offers the workers the tools to increase their

problem‐solving capacity. This strategy helps them to find out that they can always

influence the impact of a situation by: (1) changing the situation by themselves; (2)

mobilizing the support of others; or (3) accepting the situation [30]. It contributes to the

workers’ belief that they are capable of performing in a certain manner to attain goals,

and thereby strengthens the their self‐efficacy51,52. The guideline has been shown to be

effective in shortening the sick leave duration of employees who are on long‐term

sickness absence because of mental health disorders50,53.

The empowerment philosophy is based on the premise that human beings have the

capacity to make choices themselves and are responsible for the consequences of their

choices54. Varekamp and Crawford Shearer55,56 show that empowerment‐based

interventions improve health, with purposeful participation in goal attainment and

wellbeing. Empowered workers are able to instigate changes in their personal behaviour

and social situation, and also to influence the organization environment they work for54.

Behavioural change models are frequently used in the development and implementation

of health‐promoting interventions57‐60. An example of a determinant model that has been

applied to various types of health‐related behaviour is the Attitude – Social influence –

self‐Efficacy (ASE) model derived from the theory of planned behaviour51 and the social

learning theory52. The ASE model is based on the assumption that the intention to engage

in behaviour is the result of goal attitude (the positive and negative evaluation of the

expected outcome of a certain behaviour), subjective norms (the belief about what others

think of the behaviour, as derived from the behaviour and/or direct feedback of significant

others), and self‐efficacy (the confidence in being able to carry out a set of specified

Additional file

121

activities) towards performing the specific behaviour. The influence of the ASE model on

the intention to change behaviour has been examined in several studies. Research shows

that the ASE model predicts changes in injury‐preventing behaviour58, eating behaviour60,

changes in physical activity57,59 and the intention to return to work after sickness leave61.

Obviously, an ASE‐based intervention is aimed at changing the determinants for intention

into behaviour and to remove the barriers to performing the desirable behaviour.

Finally, the International Classification of Functioning, disability and health (ICF) has been

a useful framework to classify and interpret relevant aspects with regard to disability and

participation62,63.

Survey of the problems, barriers, facilitators and support needs due to ageing

A survey study has been conducted to gather information about the problems

experienced in work performance due to ageing, barriers and facilitators in the work

situation and support needs to continue throughout the working life of workers aged 45

years and older64. Problems due to ageing, with regard to a sustainable working life, were

reported by 41% of the workers; 37% reported a chronic health condition. Barriers to

performing work tasks were reported by 59% of the workers who experienced problems

due to ageing, and to continue working life in the coming years, 68% of the workers

reported support needs. Most frequently reported barriers to work participation are

physical problems (muscle function decline), cognitive problems (concentration lapses and

memory deterioration) and mental problems (energy‐driven functions based on

psychological and physiological mechanisms) due to ageing. The most frequently

experienced barriers were concentration, work‐pace and mobility; facilitators are support

from colleagues and supervisors, and opportunities for personal development. The results

show that factors to enhance the working life of workers aged 45 years and older are

found at the personal and the organizational levels. These findings emphasize the need for

a joint – organization and worker – approach.

Consultant meeting group

Based on the literature search and survey study, a concept of the intervention has been

developed and discussed during consultant meetings with experts in the field of work and

health. First the content and practicability of the intervention were discussed in one

session with two senior researchers (from national institutes with experience of

occupational health intervention programmes) and two practising occupational health

physicians. The importance of informing workers about the research as well as the content

and organization of the study were discussed during the meeting. After revision of the

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recruitment procedure and the outcomes to define a sustainable working life, a meeting

with the head of the human resources department of the participating organization took

place. During this meeting, the importance of paying attention to the ageing workforce

was presented, especially the benefits of sustainable healthy workers and the possibility

of integrating the intervention into the current human resources system. This meeting led

to some restrictions on the implementation of the intervention, namely the number of

participants, the preference of participating departments, caused by the high percentage

of older workers, and the selection on the suitability of the department, based on the

current atmosphere. In addition, departments undergoing other types of intervention

studies were excluded from our intervention study. The HRPs recommend measuring and

supporting the use of current tools, education and training, to enhance work adjustments

and personal development, because these tools are currently underused by workers.

After the second revision of the intervention, managers and supervisors at the proposed

participating organizations were informed about the content of the intervention and the

research project by their HRP. The managers and supervisors at the eligible departments,

i.e. departments with the highest percentage of workers aged 45 years and older, were

recruited by their HRPs. The researchers sent an information leaflet by post to these

managers and supervisors, and consulted with all departments interested in participating

in the study about the content of the intervention. Some parts of the concept intervention

were omitted due to lack of support of the managers or supervisors, i.e. participation of all

ages and a 2‐day training of the supervisor.


123

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7

Effectiveness of a problem‐solving based intervention to

enhance sustainable employability of ageing workers

Submitted for publication

W. Koolhaas

J.W. Groothoff

M.R. de Boer

J.J. van der Klink

S. Brouwer

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ABSTRACT

Objective: The aim of the current study is to evaluate the effectiveness of the problem‐

solving based intervention ‘Staying healthy at work’ compared to usual business.

Methods: This study was designed as a quasi‐experimental trial with a 1‐year follow‐up.

Measurements were performed at baseline, three and 12 months. The problem‐solving

based intervention provides a strategy to increase the awareness of ageing workers with

regard to their role and responsibility to create a sustainable healthy working life. The

primary outcomes were work ability, vitality and productivity. Secondary outcomes were

perceived fatigue, psychosocial work characteristics, work attitude, self‐efficacy, and work

engagement.

Results: Analyses were performed for 64 workers in the intervention and 61 workers in the

usual business group respectively. No effects on productivity and adverse effects on work

ability (B=‐1.33, 95%CI ‐2.45 to ‐0.20) and vitality (OR=0.10, 95%CI 0.02‐0.46) were found.

Positive results were found for the secondary outcomes work attitude (B = 5.29, 95%CI ‐

9.59 to ‐0.99), the self‐efficacy persistence subscale (B = 1.45, 95%CI 0.43‐2.48) and

subscale skill discretion of the psychosocial work characteristics (B = 1.78, 95%CI 0.74‐

2.83).

Conclusion: The results of the problem‐solving intervention showed no positive effects on

the three outcome measures compared to usual business. However, effectiveness was

shown on three of the secondary outcome measures, i.e. work attitude, self‐efficacy and

skill discretion. We presume that the lack of positive effects on primary outcomes is due

to program failure and not to theory failure.

Trial registration: The trial is registered with the Dutch Trial Register under number

NTR2270.

Key words: aging workforce, intervention study, ageing workers, problem‐solving

approach, solution focused, work ability

Effectiveness of the intervention

129

INTRODUCTION


social insurance systems1. Ageing is associated with a higher sickness absenteeism rate2,

reduced work ability and decreased productivity3,4. Moreover, ageing of the workforce is

associated with an increase in number of workers with chronic health conditions. There is

evidence that the presence of chronic health problems impacts on work ability5, work

disability6 and productivity4 while adjusted for age. The ageing workforce in combination

with the increase in health problems in ageing workers implies the importance of

evidence‐based interventions to enhance sustainable employability7. To date, this type of

interventions is scarce.

An important first step in developing strategies and preventive measures aimed at

maintaining and enhancing sustainable employability of ageing workers is to get insight

into the hindering and facilitating factors. In a recently published study we gathered

number and type of perceived problems, obstacles, retention factors and support needs of

workers aged 45 years and older8. For workers with a chronic health condition we found

significantly more perceived problems due to ageing as well as obstacles in performing

work tasks and support needs to continue their working life compared to those workers

without a chronic health condition. However, the type of reported problems, obstacles,

retention factors and support needs were divers but very similar in both groups. These

findings suggest that interventions aimed to enhance sustainable employability can be

similar for ageing workers with and without chronic health conditions. Moreover, it

suggests that a preventive intervention to overcome the challenge of an ageing workforce

should be able to deal with individually experienced problems and needs.

A possible strategy that might facilitate ageing workers to deal with these problems,

obstacles, retention factors and support needs is the cognitive‐behavioural process as

described by Meichenbaum and Deffenbacher9 and D’Zurilla and Goldfried10. Both

described a problem‐solving approach by which subjects identify effective or adaptive

solutions for (problematic) situations encountered in the course of everyday living. Based

on these rationales we developed the intervention called ‘Staying healthy at work’ aiming

to enhance the problem‐solving strategies of ageing workers to prolong their working life.

The strategy of the intervention was to change the workers awareness and behaviour by

emphasizing their own decisive role in attaining goals by giving them tools and support

with which they can be effective in carrying out the necessary actions. This may help them

to learn that they can always influence the impact of a situation by: (1) changing the

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130

situation by themselves; (2) mobilizing the support of others; or (3) accepting the situation

if it proofs to be unchangeable. It contributes to the workers’ belief that they are capable

of solving work‐related problems and attaining goals, and thereby strengthens their self‐

efficacy. In a previous study by Van de Klink et al. the problem‐solving approach was used

in a workers context to facilitate the return‐to‐work of employees on sickness absence

because of mental health problems11. These authors developed and evaluated an

evidence‐based guideline and showed that using the guideline approach shortened sick

leave duration12. In that study the focus was on workers on sick leave with an adjustment

disorder and thus on tertiary prevention. The occupational physician was the appropriate

mediator in facilitating those workers.

The present study is aimed at enhancing sustainable employability of ageing workers

based on individual arrangements, career development activities and aspirations. For this

primary preventive approach the supervisor is the most suitable mediator. Supervisors are

most likely to receive the first indications that accommodations are needed for workers

and are responsible for supporting and facilitating workers13,14. Therefore, supervisors

have been trained in skills to support workers in taking the necessary actions by means of

stimulating self‐direction and enhancing knowledge and competencies.

The aim of the present study was to evaluate the effectiveness of this problem‐solving

based intervention ‘Staying Healthy at Work’ in maintaining and enhancing sustainable

employability compared to usual business. In addition, a process evaluation of the

intervention was performed to explore to which extent the underlying theory and the

program delivery could account for the results.

METHODS

Study design and setting

This study was carried out as a quasi‐experimental trial. Outcomes were measured at

baseline, 3 and 12 months. A process evaluation was performed at the worker’s level at 3

and 9 months. The Medical Ethics Committee of the University Medical Center Groningen

approved the study design, the protocols and the procedures.

Study population and recruitment

The study was performed at the University Medical Center Groningen and the University

of Groningen. Participating departments of the University hospital were paediatric and

intensive care units. Participating departments of the University were technical services,


131

secretarial administrative services, financial economic affairs, human resource advice,

facility services and the library.

Selection of participants in this study was done in a two‐step procedure. First,

eligible supervisors were invited to participate in the trial. Selection of supervisors, and

thereby their workers, took place by the Human Resource Professionals (HRP’s) of the two

organisations. Inclusion criteria for potentially participating departments in this study

were: a) high percentage of workers aged 45 years and older compared to other

departments; b) no other types of intervention studies being performed simultaneously;

and c) no planned re‐organisations. Supervisors at the departments proposed by the HRPs

were invited and informed about the set‐up of the intervention by the researcher prior to

their decision to participate in this study. Those who were first to agree to participate in

this study were allocated to the intervention group until half of the potentially estimated

workers (n=131) were allocated to the intervention group. The remaining supervisors and

their workers formed the usual business group. Supervisors who were willing to

participate in the study received information about the procedure. Recruitment of the

supervisors started in June 2009.

In the second step, eligible workers of supervisors who consented to participate were

asked to participate in this study. Workers were informed about this study by their

supervisor in November 2009. Hereafter, the workers received a letter of invitation to

participate in the study, describing the aim, content and set‐up. Workers on long‐term sick

leave with no prospect of recovery, or workers who were certain to leave the job within

one year were excluded from the study. Participation was voluntarily and workers were

free to leave this study at any time without further consequences. All the workers residing

under a supervisor followed the same treatment regime, i.e. treatment allocation was at

the level of the supervisor. This was done to minimize the probability of contamination15.

The intervention ‘Staying healthy at work’

At the workers‐level the intervention comprised three stages: 1) the workers received a

booklet focused at making an inventory of (work‐related) problems, needs, and career and

personal development opportunities. For these issues the worker was asked to assess the

degree of modifiability; 2) a dialogue between worker and supervisor to discuss solutions

according to a brainstorm format; and 3) making an action plan for the next year follow‐up

period for planning and implementing the solutions. The intervention was incorporated

into the annual appraisal within the organisations.

The intervention provides a booklet for workers to prepare for the appraisal and to

complete their own action plan based on solutions which are chosen and written down by

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132

the workers themselves. Supervisors are responsible for recognizing and rewarding

excellent performance and providing coaching and feedback where needed to improve

performance deficiencies. Also they should ensure that employees have the tools,

resources, and training needed to carry out their responsibilities successfully. Therefore,

supervisors were trained how to challenge the worker to reflect on the feasibility of

solutions and how to present themselves as a source of support for the worker; not by

taking over responsibilities, but by strengthening the autonomy of the worker. The first 2

hours training focused on knowledge regarding sustainable employability, and on

problem‐solving techniques. After 2 weeks the second training (5 hours ) took place,

which consisted of an active training module in which the problem‐solving techniques

were practiced by role‐play with an actor.

Business as usual

Workers in the usual business group received their regular annual appraisal.

Primary outcome variables

Work ability was assessed with the Work Ability Index (WAI), which covers seven aspects,

each of which is evaluated with one or more questions16. The WAI is a reliable and valid

standardized measure of work ability17. Scores range from 7 to 49; higher scores indicate

better work ability.

Vitality was measured with the single item vitality scale of the 12‐Item Short Form Health

Survey (SF12) and its reliability and validity have been documented18,19. The item scores

were ‘never’, ‘seldom’, ‘sometimes’, ‘mostly’, and ‘always’.

Productivity was measured with the quantity scale of the Quality and Quantity (QQ)

method measuring productivity loss at work20. The QQ provides a reliable and valid tool

for measuring quantity and quality of work on a daily basis. Workers were asked to

indicate how much work they had performed during regular hours on their last regular

workday as compared with normal. The quantity of productivity was measured on a scale

from 0 (nothing) to 10 (regular quantity)3. The outcome was dichotomised into

productivity loss (scoring 0‐9) and no productivity loss (scoring 10). The quality of

productivity was not measured because the quality and quantity question are highly

correlated3.


133

Secondary outcome variables

Secondary outcomes were assessed at baseline and at 12 months follow‐up. Fatigue was

assessed with the 8 item subscale ‘the subjective feeling of fatigue’ of the Checklist

Individual Strength (CIS)21. The items were scored on a 7‐point Likert scale ranging from

‘Yes, that is true’ to ‘No, that is not true’. Scores were summed leading to possible scores

ranging between 8‐56; higher scores indicate higher degrees of fatigue. Psychosocial work

characteristics were measured with the Job Content Questionnaire (JCQ)22. The JCQ

consists of five subscales: job demands (5 items, range 12‐48), decision authority (3 items,

range 12‐48), skill discretion (6 items, range 12‐48), social support from supervisors (4

items, range 4‐16) and co‐worker support (4 items, range 4‐16). Each item was rated on a

4‐point scale from ‘strongly disagree’ to ‘strongly agree’.

Perceived work attitude was measured with the Dutch Language version of the Work

Involvement Scale (WIS‐DLV), which covers 6 items on a 4 point scale (strongly disagree to

strongly agree). Higher scores (range 0‐100) indicate more positive attitudes towards

work23. Self‐efficacy was measured with the standardized Dutch version of the General

Self‐Efficacy Scale (ALCOS‐16)24, which assesses the subjects’ expectations of their general

capacities25. The instrument consists of 16 items assessing the subscales ‘willingness to

exert effort in completing the behaviour’ (range 6‐30), ‘persistence in the face of

adversity’ (range 6‐30), and ‘willingness to initiate behaviour’ (range 4‐24). The five

answering categories range from ‘strongly disagree’ to ‘strongly agree’; a higher score on

this questionnaire indicates higher self‐efficacy. Work engagement was measured with the

short Dutch version of the Utrecht Work Engagement Scale (UWES‐9)26. The nine items

reflect three subscales covering the underlying dimensions of engagement. These

subscales vigour, dedication and absorption (each subscale 3 items) are scored on a 7‐

point frequency rating scale ranging from ‘never (0)’ to ‘always/ever’ (6).

Potential confounders

At baseline, data on potential confounders at the level of the workers was assessed by

questionnaire including age, gender (male/female), education (low = lower vocational

education/ medium = intermediate secondary or vocational education/ high = higher

vocational education and university), occupation (executive/ secretarial or administrative/

policy/ management), sector (health care/ education), shift work (yes/ no), duration of

current position and years paid work (0‐10/ 11‐20/ 21‐30/ 31‐40/ >40years).

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134

Process evaluation at the workers level

The process evaluation was carried out by using a questionnaire at the worker’s level to

measure whether the intervention was carried out as intended. To what extent all

intended intervention components were performed was collected with registration forms

by the supervisor (e.g. appointment dialogue and performing dialogue) and by the

researchers (e.g. preparing for the dialogue with first step of the booklet, to draw up an

action plan, and performing described action(s)). Workers in the intervention group were

asked (yes/no) to evaluate the content and the relevance of the information leaflets they

received in order to prepare for the dialogue, to what extent they experienced support

from the booklet and whether the focus on the modifiability of situations motivated them

to plan and implement solutions. The quality of the dialogue (rated on a 5‐point scale from

excellent to very poor), the duration of the dialogue (in minutes) and the support they

experienced from the supervisor were assessed.

Statistical analysis

All statistical analyses were carried out at the workers’ level and according to the

intention‐to‐treat principle. The chi‐square test (ordinal and nominal variables) or t‐test

(mean scores) were used to compare differences on baseline characteristics between the

intervention and usual business group. For the primary outcomes, we performed linear

(work ability), ordinal (vitality), and logistic (productivity) multilevel analyses. We had

planned to incorporate three levels (supervisor, worker, observation) in all models.

However, random coefficients at the supervisor level did not improve model fit. Thus, two

levels (worker and observation) were incorporated in the models. We tested for

interactions between the intervention and time to follow‐up by incorporating interaction

terms in all multilevel analyses. For the secondary outcomes we performed linear

regression analyses. All analyses included adjustment for baseline levels of the outcome,

baseline levels of the other primary and secondary outcomes and for the potential

confounders. A detailed description of the sample size analyses has been provided

elsewhere27. The multilevel analyses were performed with MLWin version 2.24. Linear

regression analyses were carried out with the Statistical Package SPSS version 18.0 (SPSS

Inc. Released 2009, Chicago: SPSS Inc). For all analyses a two‐tailed p‐level of <.05 was

considered to indicate statistical significance.


135

RESULTS

During the recruitment period 28 supervisors were approached to participate in this study.

Nine supervisors declined for reasons such as upcoming reorganisation and time pressure.

The remaining 19 supervisors were allocated in either the intervention (n=12) or usual

business group (n=7). Following the allocation of the supervisors, the total of 236 workers

were divided to the intervention group (n = 129) or usual business group (n = 107). An

overview of the recruitment flow is presented in Figure 1.

136

Figure 1: Flow diagram

of the participants through

the phases of the trial


137

Non‐participation and loss to follow‐up

Workers who did not meet the inclusion criteria were excluded from this study (n=16). The

most common reasons for exclusion were sick leave for longer than 1 year (n=10) and

upcoming pension (n=6). In the intervention group, 3 workers refused to participate, and 9

worker did not participate due to unknown reasons. In the usual practise group, 36

workers did not participate in this study because they refusal to participate (n=5) or due to

unknown reasons (n=31). There was no data on demographic or work related outcomes of

these workers to compare them with workers participating in this study.

During the intervention, 2 supervisors in the intervention group were unable to

implement the intervention because of unforeseen reorganisation of the department for

one of the supervisors and long‐term sickness of the other supervisor. Therefore, we lost

26 workers in the intervention group after the baseline measure. For the remaining

workers, data of both follow‐up measures was missing for 18 and 5 workers in the

intervention and usual business group respectively. These 49 workers who were lost after

baseline had a lower educational level (p =.003), were more fatigued (p =.008) and

reported lower scores on vitality (p=.004), and on the self‐efficacy scales willingness to

exert effort in completing a behaviour (p =.007) and willingness to initiate behaviour

(p=.026). Data of 125 workers was available for the analyses; 64 workers in the

intervention group and 61 workers in the usual business group respectively. Of these

there was no data for 12 workers at T1 (intervention group n=9; usual practise n=3) and 13

workers at T2 (intervention group n=5; usual practise n=8).

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138

Table 1: Baseline characteristics of the total population, intervention group and usual business group

All workers Intervention

group

Usual business

group

Characteristics N % N % N %

Age in years (mean, SD) 123 52.4 (5.3) 52.8 (5.6) 51.9 (4.8)

Gender (n=145)

Female 117 81 58 73 59 89

Male 28 19 21 27 7 11

Education (n=145)

Low 21 14 12 15 9 14

Medium 61 41 30 38 31 48

High 63 43 38 47 25 38

Occupation (n=146)

Executive 106 72 66 83 40 61

Secretarial or administrative 26 18 7 9 19 29

Policy 9 6 6 7 3 4

Management 5 4 1 1 4 6

Sector (n=148)

Health care 106 72 64 78 42 64

Education 42 28 18 22 24 36

Shift work (n=145)

Yes 89 61 59 75 30 45

No 56 39 20 25 36 55

Duration current position in years (n=144)

0‐10 27 19 15 19 12 19

11‐20 30 21 15 19 15 23

21‐30 46 32 28 35 18 28

31‐40 36 25 21 26 15 23

>40 5 3 1 1 4 7

Years paid work (n=145)

0‐10 1 1 1 1 ‐‐ ‐‐

11‐20 20 14 11 14 9 14

21‐30 53 36 28 35 25 38

31‐40 62 43 37 47 25 38

>40 9 6 2 3 7 10


139

Baseline Characteristics

The baseline characteristics of the workers in the intervention and usual business group

are presented in Table 1. Significant differences at baseline between the intervention and

usual practise were found on gender, occupation and shift work. The intervention group

consisted of higher percentages males (27% vs. 11%; p=.015), more executive workers

(83% vs. 61%) and less secretarial workers (9% vs. 29%; p=.005), and more shift workers

(75% vs. 45%; p=.001) compared to the usual business group. Table 2 shows the

frequencies and mean scores of the outcome variables at baseline and follow‐up

measurements. No significant differences were found on baseline between the

intervention and usual business group, except for the scale job demands, which showed a

small difference (32.86 vs. 32.07; p=.004).

Primary and secondary outcome measures

The results regarding effectiveness of the intervention with respect to the primary and

secondary outcome measures are presented in Table 3. A significant adverse effect during

follow‐up was found for work ability (B=‐1.33, 95%CI ‐2.45 to ‐0.20) and vitality (OR=0.10,

95%CI 0.02‐0.46). This means that workers in the intervention group had a 1.33 points

lower mean score on the WAI than workers in the control group and that they had a 0.10

times higher odds of being in a higher vitality category than the persons in the control

group. We found no statistically significant difference between both groups on

productivity. No interaction effects between the intervention and time to follow‐up for

any of the primary outcomes were found. Positive significant results in favour of the

intervention group were found for the secondary outcomes work attitude (B = 5.29, 95%CI

‐9.59 to ‐0.99), self‐efficacy (persistence subscale) (B = 1.45, 95%CI 0.43‐2.48) and the

subscale skill discretion of the job content questionnaire (B = 1.78, 95%CI 0.74‐2.83).

140

Table 2: Percentages and m

eans of the primary and secondary outcomes at baseline, 3 and 12 m

onths

Intervention group

Usual business group

Baselin

e3 m

onths

12 m

onths

Baselin

e3 m

onths

12 m

onths

N = 82

N = 55

N = 59

N = 66

N = 58

N = 53

Primary outcomes

Work ability (mean, SD)

39.0

5.4

38.9

5.3

38.7

5.2

38.9

5.4

38.9

5.1

38.9

4.7

Poor (%

)7

4

46

02

Moderate (%)

21

22

22

22

31

23

Good (%)

50

55

56

52

51

58

Excellent (%

)22

18

18

20

18

17

Vitality

Never (%)

00

0

00

0

Seldom (%)

32

2

23

0

Sometim

es (%)

18

20

20

16

16

25

Mostly (%)

74

70

73

79

71

68

Always (%)

67

5

310

8

No productivity loss (%)

66

76

61

67

76

64

Secondary outcomes

Mean

SDMean

SD

Mean

SDMean

SDMean

SDMean

SD

Perceived fatigue

18.89

9.4

19.53

10.4

19.58

10.7

21.55

11.4

Job content

Job dem

ands

32.07

4.9

31.71

5.4

32.86

6.8

31.15

5.5

Decision authority

33.90

6.0

34.37

5.9

35.64

7.1

34.94

7.4

Skill discretion

38.63

4.4

38.31

4.0

38.15

5.1

37.21

4.4

141

Table 2 continued

Intervention group

Usual business group

Baselin

e3 m

onths

12 m

onths

Baselin

e3 m

onths

12 m

onths

Secondary outcomes

Mean

SDMean

SD

Mean

SDMean

SDMean

SDMean

SD

Support from supervisor

10.84

2.2

10.61

2.1

11.68

2.3

11.71

2.7

Co‐w

orker support

12.20

2.1

12.22

1.5

12.71

1.8

12.70

1.5

Perceived work attitude

28.75

15.3

27.49

13.5

29.55

15.1

30.50

15.0

Self‐efficacy

67.13

6.9

65.85

6.1

66.30

8.9

64.70

10.5

Willingness to exert effort in

completing the beh

aviour

25.88

3.5

25.11

3.2

25.47

3.6

24.58

4.4

Persisten

ce in

the face of

adversity

25.24

2.9

25.24

2.9

24.89

3.6

24.79

3.7

Willingness to initiate beh

aviour

16.01

2.8

15.48

2.8

15.94

3.2

15.34

3.4

Work engagemen

t total

4.34

0.9

4.50

0.9

4.29

1.1

4.44

0.8

Vigour

4.49

0.9

4.55

1.0

4.46

1.0

4.62

0.9

Ded

ication

4.65

1.0

4.84

0.9

4.69

1.2

4.77

1.0

Absorption

3.89

1.2

4.11

1.1

3.73

1.2

3.94

0.9

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142

Table 3: Results of the regression analyses to measure the of the intervention on primary and secondary outcomes

Outcome measure* B OR p‐value 95%CI

Lower Upper

Primary outcomes+

Work ability ‐1.33 0.021 ‐2.45 ‐0.20

Vitality 0.10 0.003 0.02 0.46

Productivity 0.83 0.779 0.23 3.00

Secondary outcomes

Perceived fatigue ‐0.11 0.935 ‐2.83 2.61

Job content

Job demands ‐0.82 0.344 ‐2.53 0.89

Decision authority ‐0.55 0.557 ‐2.38 1.29

Skill discretion 1.78 0.001 0.74 2.83

Support from supervisor 0.17 0.659 ‐0.59 0.94

Co‐worker support 0.03 0.906 ‐0.41 0.46

Perceived work attitude 5.29 0.016 ‐9.59 ‐0.99

Self‐efficacy

Willingness to exert effort in

completing the behaviour 0.11 0.84 ‐0.95 1.17

Persistence in the face of

adversity 1.45 0.006 0.43 2.48

Willingness to initiate behaviour ‐0.47 0.288 ‐1.33 0.40

Work engagement

Vigour ‐0.21 0.118 ‐0.47 0.05

Dedication ‐0.03 0.846 ‐0.31 0.25

Absorption ‐0.07 0.692 ‐0.40 0.26

* Analyses on outcome measures were adjusted for age, gender, education, occupation, sector, shift work, duration current position and years paid work + Primary outcomes were analysed with linear (work ability), logistic (productivity) and ordinal (vitality) multilevel analyses


143

Process evaluation

Of the workers in the intervention group, 54 (66%) filled out the process evaluation

questionnaire after 3 months. The first step of the intervention (inventory and

modifiability) was performed by 91% (n=49) of the workers. The dialogue took place

within 3 months after the baseline measurement for 52 (96%) workers. Preparation of the

action plan in the third step of the intervention was performed by 29 workers (56%); 27 of

these workers received feedback of their supervisor. Satisfaction with the content and

relevance of the information, leaflets and booklet of the intervention was reported by 53

workers (96%). The first step of the intervention supported 32 workers (65%) to formulate

opportunities for personal development, career opportunities and experienced problems

in the work situation. Specifying the modifiability motivated 31 workers (63%) to plan

actions. The average time of the dialogue was 38 minutes (range 5‐60 minutes) and the

communication between workers and supervisor was generally good (n=32; 62%) to very

good (n=17; 32%). Three workers required a follow‐up meeting with the supervisor.

After 3 months 43% of the workers (n=23) reported that the intervention had increased

their ability to clarify and explore problems with work participation and career aspiration.

About half of the workers reported to have become more capable in conducting a

dialogue with the supervisor about sustainable work participation (n=25; 46%) and to set

up a structured action plan to improve work conditions after the intervention (n=23; 43%).

Fifty‐four per cent (n=29) of the workers stated that the intervention had made them

aware of the responsibility to create a healthy workplace. The intervention contributed to

more self‐confidence in changing the work situation for 37% (n=20) of the workers and to

enhanced skills to discuss work performance with the supervisor for 35% (n=19). To a

lesser extent, the intervention resulted in better functioning at work (n=8; 15%) and more

pleasure in the work situation (n=10; 19%). The same trends were observed after nine

months (Table 4).

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144

Table 4: Results of the process evaluation at workers’ level after 3 and 9 months

After 3 months

(n=54)

After 9 months

(n=50)

n % n %

The intervention has increased my ability to:

…clarify and explore problems with work

participation and career aspirations

23 43 19 38

…establish a dialogue with the supervisor about

sustainable work participation

25 46 24 48

…set up a structured plan to improve the work

conditions

23 43 19 38

…perform my work as before 13 24 7 14

Through the intervention I am:

…more aware of the responsibility to create a

healthy and motivating work place

29 54 28 56

…functioning better at work 8 15 7 14

…taking more actions to improve the work

conditions

23 43 17 34

The intervention contributed to:

…more pleasure in the work situation 10 19 8 16

…more self‐confidence to accomplish changes in

the work situation

20 37 14 28

…better skills to discuss work functioning with the

supervisor

19 35 13 26


145

DISCUSSION

The problem‐solving intervention ‘Staying healthy at Work’ designed for workers to

enhance sustainable employability showed no superior effect on productivity and a

negative effect on work ability and vitality compared to usual business. However, positive

effects were found on the secondary outcome measures perceived work attitude, the self‐

efficacy subscale persistence in the face of adversity and the subscale skill discretion of

the psychosocial work characteristics.

To our knowledge this study is the first prospective controlled trial aimed to support

sustainable employability of ageing workers by means of an intervention focussing on

enhancing the problem‐solving capacity of workers. Most intervention studies aimed at

promoting and enhancing the participation in working life of workers, provide a lifestyle

training programme to improve job retention, increase vitality or to decrease work

disability28‐30. This study provides workers a guidance how to prolong work participation in

good health by enhancing the workers’ awareness and behaviour by emphasizing their

own decisive role in attaining goals and carrying out the necessary actions. As the labour

participation of specifically ageing workers need to be extended, the results of this study

are innovative and provide valuable information for (occupational) health researchers,

policy makers and employers. The fact that we found no or negative effects on the

primary health‐related outcomes is in line with earlier studies focussing on work‐site

interventions to support sustainable employability31,32. We have used the theoretical

model of Kristensen to discuss our results33.

Based on the results of previous problem‐solving intervention studies we presume that

our negative findings on the primary outcomes variables do not result from theory failure.

These studies showed that problem‐solving intervention studies on work related

outcomes had a superior effect on sickness absence12, return to work12,34, prevention of

depression35, and treatment of anxiety disorders36. Moreover, it is also shown that a

problem‐solving training in the workplace can increase problem‐solving skills and

problem‐solving self‐efficacy in the course of improving positive affect, job satisfaction,

and life satisfaction37. Therefore, our assumption that a self‐directed cognitive behavioural

intervention enhanced the problem‐solving capacity of ageing workers towards

sustainable employability might be effective is still valid. In our study, the positive results

on the secondary outcomes work attitude, persistence in the face of adversity and skill

discretion acknowledge that the intervention changed the awareness and behaviour of

workers to enhance work participation. In addition, the process evaluation on the

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146

workers’ level confirms this. Therefore, we assume that lack of impact of the intervention

on the primary outcome measures must be explained by program failures of the

intervention33. We will elaborate on both aspects of program failure: dose delivered and

dose received.

On the level of dose delivered the short duration of the training of the supervisors might

explain the lack of the effectiveness of the intervention on the primary outcome

measures. Knowledge and basic skills in communication of the supervisors was low and,

during the training, a lot of time was spent on these basic skills instead of the problem‐

solving approach. Moreover, the duration and frequency of the training for supervisors

(two sessions of two and five hours respectively) might have been too short to transfer

the acquired skills into attitude and practice. Prior to the implementation, the research

team suggested to train the supervisors for two days or three training sessions to

accomplish the targeted level of knowledge and skills necessary to perform the

intervention. However, the intervention was conducted as part of the normal activities of

an organisation and thereby time of the supervisors to participate in the study was

limited. At the organisational level they were convinced that their supervisors were

trained well and the supervisors’ skills were in line with the skills necessary to perform the

dialogue. Therefore, we had to deal with restrictions in time investment of the

supervisor’s during implementation of the training.

On the workers’ level (dose received), defining a structured action plan after the dialogue

was not carried out by 44% of the participants. This low adherence might have

contributed to the low effectiveness of the intervention. Reasons for not defining an

action plan were that workers did not have the ability to translate the points discussed

during the dialogue into appropriate actions, high work pressure, lack of knowledge about

available interventions in the organisation or lack of motivation. In contrast, the first step

of the intervention was performed by almost all workers. This discrepancy in adherence

between parts of the intervention might also partly explain our findings. The first step

makes workers aware of their own responsibility, obstacles, retention factors and needs

towards sustainable employability. As a consequence, workers can experience (emotional)

feelings of increased (work) load and decreased work ability. The more positive

experiences and effects result from the next, solution focused, steps of the intervention.

These steps were not taken by many workers and, if taken, their effect appears later. The

positive results on the secondary outcomes in our study imply that the intervention

changed the perspectives of workers about awareness and responsibility of sustainable

employability in a positive way. These results are in line with results of other behavioural


147

intervention studies, that have shown that cognitive behavioural interventions improve

self‐efficacy, job satisfaction and motivation towards return to work28,38 and coping with

chronic conditions39,40. In our intervention, workers understood their own responsibility

towards a healthy and sustainable working life, but missed the optimal benefit of the later

steps of the intervention. Therefore we assume that the intervention might be effective in

the long term on enhancing sustainable employability if program failures are avoided.

In addition to the time frame of the intervention, which is discussed above in relation to

program failures, the non‐randomised design might have caused bias. The earlier the

supervisor agreed to participate, the more likely it was that he/she was allocated in the

intervention group. The departments in the intervention group were comparable to the

control group, because the departments which were asked to participate in the study

were matched on percentage of ageing workers and comparable job tasks to overcome

this source of bias in the study design. However, it might be possible that especially

cooperative and committed supervisors, who already put a lot of effort in sustainable

employability of their ageing workers, were allocated to the intervention. Contamination

between supervisors in the control and intervention group cannot be excluded. Although

we applied cluster randomisation to avoid contamination between workers, supervisors

from both groups might have had common activities inside the organisation and could

have discussed the study. Furthermore, there was a small difference between the

intervention and the usual business group at baseline for the secondary outcome measure

job demands. However, this and other differences between both groups were taken into

account in the analyses.

Despite of the above mentioned shortcomings, there also were some successful elements

in our intervention study. The results suggest that workers in the intervention group were

better able to identify or discover effective solutions for specific problem encountered in

working life compared to workers in the usual business group who received an annual

appraisal. Although both groups of workers receive an annual appraisal, the results shows

that the intervention activates workers to be aware of their own responsibility for actions

towards a healthy and motivating work place. This is in line with experiences of the

management of the participating organisations, because in practice most workers feel

they are being judged and marked on performance. Workers do not discuss what they

enjoy doing, where they have difficulties, aspirations and opportunities because they

don’t know how to prepare beforehand. Moreover, the intervention had the strength of

an integrated approach which provides close collaboration between the worker and

supervisor as well as human research management that ensures that employees have the

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tools, resources, training, and development needed to carry out their responsibilities

successfully. Earlier research has shown that a more participatory and supportive

approach of the supervisor might help workers to identify their challenges and implement

solutions41. The close cooperation with the human resource professionals during the

implementation ensured that the intervention was in line with the existing organisational

policy. However, during implementation it is important to take into account the fidelity

(delivering the intervention as planned), because non‐fidelity will dilute the difference

between the intervention and control group. An additional asset of the intervention is that

the method can be incorporated into the cycle of annual appraisal between worker and

supervisor within the organisations.

Future research of intervention studies at workplaces based on an integrated problem‐

solving approach needs to be done with strict program integrity to establish whether or

not such an intervention is effective in increasing sustainable employability. What is now

needed is a randomized controlled trial including a detailed process evaluation on both

workers and supervisors level to evaluate the effectiveness of the intervention. Program

failures might be prevented by a) development of a monitoring system to support the

setup of a structured plan after the dialogue with specific, well‐defined and realistic goals

and to perform the actions and solutions described in this plan, and b) telephone support

and the organisation of peer groups for supervisors during the intervention period to

improve their (communication) skills and supportive role based on the problem‐solving

approach. In addition, information about the quality of the annual appraisal and the

received support of the supervisors in the control group could show to what extent the

intervention contributes to a healthy working life compared to the traditional appraisal. If

the intervention is proven effective, it is important to investigate the usability and

effectiveness of the intervention in different occupational groups.


149

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8

General discussion

General discussion

155

The main objectives of this thesis were to provide insight into the needs and determinants

regarding a sustainable working life by conducting a survey study, and to develop and

evaluate an intervention aimed to enhance sustainable employability among workers aged

45 years and older, with and without a chronic health condition. This final chapter

presents and discusses the main findings in the light of those objectives, and also

discusses the methodological implications and recommendations for future use of the

intervention, and for policy and practice.

MAIN FINDINGS AND INTERPRETATION

Problems experienced, obstacles, retention factors and needs

In our sample, 42% of workers aged 45 years and older experienced problems due to

ageing. About a quarter of those workers (26%) reported obstacles to performing their

work. Retention factors were reported by 82% of the workers, and 38% reported that they

had special support needs if they were to continue working over the coming years.

Problems due to ageing were especially related to decreased physiological and

psychological functioning, for example, energy level, sustainable attention, recall memory,

visual acuity, physical condition and muscle strength functions. Perceived support needs

concerned work‐related environmental factors in particular, for example, working fewer

hours, task reduction, reducing time pressure and improvement of the physical conditions

in the work place (chapter 2). Our results showed that ageing is a challenge for a lot of

workers from the age of 45 years onwards during working life, which implies the

importance of attention to retention factors and needs for maintaining and increasing

sustainable employability.

Determinants of work ability

The results of our cross‐sectional survey showed significant associations between some

individual characteristics, work conditions, psychosocial factors and work ability. Older

age, the presence of a chronic health condition, lower education, executive work, and

physically demanding jobs were associated with a lower work ability level (chapter 4). We

used the single‐item work ability score to determine these factors in a sample of workers

aged 45 years and older working in different occupations and organizations for the current

work ability compared with the lifetime best. Our findings were comparable with several

previous prospective cohort and cross‐sectional studies that used the total work ability

score1‐7, which contains many questions that only indirectly measure work ability (e.g. sick

leave taken during the past year, mental resources and vitality)8. Those studies were often

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performed in a specific group of the working population such as municipal workers and

home care workers2,9.

Furthermore, we found that an active coping style is positively associated with work ability

and this association is not influenced by higher levels of job control or instrumental

support. We found negative associations between both emotional and avoidance coping

styles and work ability, but found no interaction effects of emotional support on those

negative associations (chapter 5). To our knowledge, this is the first published study that

examines the relationship between coping styles and work ability level.

Different types of ageing

In this thesis the target group was workers aged 45 years and older. By reason of research

we had to set an age criterion in agreement with other studies7,10‐12, although we realise

that any specific age is arbitrary and cannot be regarded to be a watershed in itself in

terms of defining who is old and who is not. Whereas ageing refers to many changes in

biological, psychosocial and social functioning over time13‐17 and is not simply an effect of

time (i.e. one’s chronological or calendar age), we focused also on other types of ageing

like functional ageing (chapter 3). We operationalized functional ageing in terms of

outcomes of health status, that is, the presence of a chronic health condition (yes/no) and

perceived health, measured with subscales of the SF‐36.

More than one third of the workers in our study population (37%) reported the presence

of a chronic health condition (chapter 3), which is consistent with previous findings in the

Dutch working population18,19. Workers with a chronic health condition scored lower on

the perceived health subscales compared to workers without a chronic health condition

(chapter 4). Univariate analyses showed that lower scores on measures of perceived

health status were associated with more commonly experienced problems, greater

numbers of obstacles, more support needs, fewer experienced retention factors and less

chance on a good or excellent work ability score (chapter 3). Moreover, the measures of

perceived health status were strongly related to the presence of a chronic health

condition and largely explained its association with work ability (chapter 4). This is

reasonable because the subscales of the perceived health questionnaire (SF‐36) are multi‐

item scales which assess distinct aspects of health and can better determine health status

than a single‐item dichotomous question about the presence of a chronic health condition

(yes/no). Other studies have shown that perceived health problems contribute to an early

exit from the labour market20‐24.

General discussion

157

As well as chronological and functional age, Kooij et al. also defined psychosocial and

organizational age25. The former concerns how old an individual feels, looks and acts, and

how old the person desires to be. The most common reason for starting to feel older was

change in health26,27 and previous results indicated that especially feeling old relative to

one’s chronological age was positively associated with several indicators of job‐related

strain across several countries28. Organizational age refers to the aging of individuals in

jobs and organizations25. Changing jobs gives you a broader base of experience and a more

varied background creates a greater demand for your skills. Depth of experience means

that workers’ are more valuable to a larger number of employers which increase their

sustainable employability. In this thesis we did not examine the relation between

psychosocial, organizational and chronological age. Although these different

conceptualizations of age are often interrelated. They might have distinct effects on work‐

related attitudes25. Therefore, it is sufficient to note here that future research requires

paying attention to different conceptualizations of ageing with regard to sustainable

employability.

Stratified analyses of older workers with and without a chronic health condition showed

no substantial differences in psychosocial factors and work conditions associated with

work ability (chapter 4). However, the explained variance in work ability score was 42.8%

for workers with a chronic health condition, compared to 28.7% for workers without a

chronic health condition. These findings suggest that workers with a chronic health

condition might benefit the most from a policy focusing on enhancing the associated

variables.

The association between active coping and work ability was stronger for workers with a

chronic health condition than for workers without a chronic health condition, and this

association was strengthened by job control (chapter 5). This is consistent with previous

studies which found that people with a moderate to high impairment in physical function

and emotional well‐being reported more frequent use of active coping strategies29. For

example, a longer duration of chronic fatigue syndrome resulted in the greater use of an

active coping approach30. This suggest that the health condition provides an additional,

partly controllable challenge to adapt to work demands. A strong focus on an active

coping style might almost be a prerequisite to enhance ability in controllable situations.

Development of an intervention

The findings of our survey study showed that the determinants of sustainable

employment were related to the worker’s individual situation (e.g. presence of chronic

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health condition, problems, needs, occupation, coping style). Based on the workers’

responses we found that, in particular, individual adjustments to the work situation are

needed to enhance sustainable employability, such as task reduction, reducing time

pressure, improvement of the physical conditions in the work place and ergonomic

adjustments (chapter 2). In addition, workers become increasingly responsible for their

own career in the last decade due to changes in the labour market. Workers need to be

aware of their own responsibility and decisive role in creating and maintaining a healthy

work life. Therefore, we expected that a tailored approach would be necessary to enhance


Since individual accommodation to the work situation should be coordinated with a

supervisor, an intervention to increase sustainable employability should emphasize good

cooperation between the worker and supervisor. Supervisors are most likely to see the

first indications that individual accommodation is required31,32. It has been shown that a

more participatory and supportive approach by the supervisor might help workers to

identify the challenges and implement solutions to increase job performance33,34.

Furthermore, for employers, it is important that an intervention designed to increase

sustainable employability accords with existing practice, policy and available tools in the

organization. Therefore, our intervention was incorporated into the annual appraisal.

Based on these findings, we developed an intervention called ‘Staying Healthy at Work’.

Our intervention offers a tailored approach to enhance sustainable employability, by

increasing the workers’ resources and their ability to continue working until retirement, in

good health. (chapter 6). The intervention is based on encouraging a self‐directed

cognitive behavioural process that will enhance the workers’ problem‐solving capacity,

and entails a partnership between the employer and worker, ultimately aiming to increase

the problem‐solving capacity of both worker and supervisor. Although this should involve

support from others, the workers themselves are mainly responsible for the actions

required and for implementing the solutions.

The purpose of our intervention was to increase the workers’ awareness and change their

behaviour by emphasizing their own decisive role in attaining goals, giving them tools and

support with which they could be effective in carrying out the necessary actions. This is in

line with our finding that adapting an active coping style is an effective way to increase

work ability (chapter 5). The first stage of the intervention is the key component. Workers

create an inventory of work‐related problems, needs and career and personal

development opportunities. To help them to discover that they can influence the impact

General discussion

159

of a situation they were invited to rate the ‘influenceability’ of the situation in one of the

three categories: (1) changing the situation themselves, (2) mobilizing the support of

others or (3) by accepting the situation if it proves to be unchangeable. This contributes to

the worker’s belief that they are capable of solving work‐related problems and attaining

goals, and thereby strengthens their self‐efficacy. In the second stage, possible solutions

are discussed with the supervisor, while in the third stage workers set up an action plan

and implement the solutions. We expect that the intervention will make workers aware of

the opportunities and their own responsibility to prolong their working life and remain

employed in good health.

Evaluation of the intervention

The intervention ‘Staying Healthy at Work’ was evaluated in a quasi‐experimental trial

(n = 125), among nurses (paediatric and intensive care units) and university employees

(technical services, secretarial administrative services, financial affairs, human resource

advice, facility services, and the library). The intervention was implemented as intended

and participation was voluntary.

The intervention had no effect on productivity and a small but negative effect on work

ability and vitality (chapter 7). Additional analyses of the secondary outcomes showed that

work attitude, self‐efficacy and skill discretion increased significantly in the intervention

group compared to the control group. After 12 months, the intervention had contributed

to an increased awareness among more than half of the workers concerning their own

responsibility to create a healthy and stimulating workplace. In addition, 40% of the

workers improved in their ability to conduct a dialogue with their supervisor about

sustainable work participation and setting up a structured action plan.

Explanations for the lack of effect on the primary outcomes can be found on different

stages of the intervention. On the workers’ level, we found a discrepancy in adherence

between the first stage of the intervention (inventory and dialogue) and the third stage

(the action plan). While the first two steps of the intervention make workers more aware

of their problems, the opportunities, needs and personal responsibility to lead a healthy

and motivated working life, they do not provide the positive emotional impetus required

to take the final step. Therefore, the workers might have missed out on the optimal

benefit of the intervention. A monitoring system to support the setup of a structured plan

after the dialogue, with well‐defined actions and solutions to enhance sustainable

employability, might increase workers’ adherence.

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On the level of the supervisors, the amount of time available to train the supervisors in a

problem‐solving approach and develop the required skills might have been too short to

transfer the acquired skills into practice. Supervisors were found to be unaware of how to

present themselves as sources of support, concerned with the problems experienced by

workers. Because the implementation of the intervention occurred during working time,

the number and total length of training sessions for supervisors was limited to a first

session of two hours and a second session of five hours. Role play with an actor, used

during the supervisors’ training session, focused on improving the skills of supervisors in

encouraging workers to assume greater responsibility for their actions in order to enhance

sustainable employability. This focus indicates that supervisors often take over the

responsibility to find solutions, which may be counter‐productive. In future, it might be

helpful to support the supervisors by using peer‐group sessions during the intervention

period to improve their communication and other relevant skills. This supportive role

might compensate for the problems associated with the short period of time available for

training.

Another reason which might explain why we did not find a positive effect on the primary

outcomes could be the short follow‐up. Implementation of the intervention makes

workers aware of their own responsibility, the obstacles, retention factors and needs

regarding sustainable employability. As a consequence, workers can experience feelings

associated with increased work load and decreased work ability. The third stage of the

intervention provides a strategy to change the situation, but the workers need time to

commence the action and transform their work situation or personal attitude step by step.

It might be the case that performing and integrating the solutions in the workplace takes

some time.

It is also plausible that we did not find an effect because supervisors were already

concerned about sustainable employability. We cannot rule out that supervisors in the

usual business group and control group also paid attention to the sustainable

employability of their workers.

In addition, people aged 45 years and older who are still working might be a select,

relatively healthy group of the general population of this age. This phenomenon refers to

a healthy worker effect, which is often encountered in occupational situations 35,36. In our

cohort, the healthy worker selection is probably stronger than in the current population of

ageing workers. The healthy worker effect might lead to an underestimation of the

existing impact of ageing on work participation. Moreover, while participation in the study

General discussion

161

was voluntary, it is possible that healthy workers who already put a lot of effort into

sustainable employability were more likely to choose to participate.

The positive results on the secondary outcomes in our study imply that the intervention

positively influenced the perspectives of workers concerning their awareness and of

feeling responsible for sustainable employability. These results are in line with those of

other intervention studies on behaviour37‐39 and coping with chronic conditions40,41. In

those studies the cognitive behavioural interventions change the workers’ attitude and job

satisfaction, which has potential impacts on work performance and product quality. For

example, by focusing more and earlier on work‐related aspects and return to work for

workers with common mental disorders the functional recovery in work substantially

speeded up. Moreover, cognitive behavioural interventions have become common

successful alternatives to traditional medical and active rehabilitation approaches for

workers with low back pain.

METHODOLOGICAL CONSIDERATION

The study is based on a considerable sample size of workers who undertook various

occupational activities (e.g. physical work, back office, health care, teaching and cleaning)

and were employed in different organizations. A mixed method approach was used, which

means that quantitative and qualitative research complemented each other, providing

insight into the workers’ views and experience of ageing problems and the determinants

and adaptation strategies associated with work ability. It provided an extended insight

into how to enhance sustainable employability and the differences between workers with

and without a chronic health condition.

To our knowledge this is one of the first intervention studies that evaluated a worksite

intervention consisting of a strategy aimed to promote the problem‐solving capacity of

ageing workers and, in turn, sustainable employability. As prolonging working life is

important in today’s society, the outcomes of this study are therefore not only innovative

but also provide valuable information. However, some methodological issues should be

taken into consideration about the survey study, intervention study and measurements.

Survey study

Design

The cross‐sectional design of the survey study did not permit exploration of causal

relationships between the associations we found. Nevertheless, the results are still of

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interest, as they provide an initial insight into factors that are important for interventions

on work ability among workers aged 45 years and older, with and without a chronic health

condition.

Response rate

The overall response rate of 36% for the survey study was considered to be satisfactory

and is regarded to be reasonable for anonymous survey studies in the Dutch working

population 42. As participation in the survey was voluntary and no information was

available about the non‐respondents, result biases related to selective participation

cannot be ruled out. However, there is no reason to expect that workers with problems

returned the questionnaire more or less frequently than other workers. The questionnaire

addressed a variety of themes and did not emphasize problems with ageing, chronic

health conditions or work participation.

Selection bias

This study was explorative in nature because we used a descriptive design to increase our

knowledge of the workers’ experiences of problems due to ageing, obstacles they faced,

retention factors, their needs if they were to continue working and the differences

between workers with and without a chronic health condition. Furthermore, the self‐

reporting nature of the study could not be externally validated. Consequently, there may

be some bias in the classification of respondents on the basis of self‐reported data,

resulting in an underestimation of the differences and associations studied. However, it is

known from the literature that the self‐reporting of health status and of certain physical

chronic diseases (diabetes, cardiovascular disease, musculoskeletal and respiratory

problems) is reasonably reliable43. Therefore, we do not expect that the self‐reporting of

health and problems due to ageing introduced any significant bias, at least for these kinds

of health conditions. However, this expectation is based on a limited number of studies

concerning physical conditions and might not be generalizable to other physical or mental

health conditions.

Intervention study

Design

The intervention study meets most of the CONSORT criteria for high quality clustered

trials44,45. We used a quasi‐experimental design because a randomized controlled trial was

not an option when implementing the intervention in practice (chapter 7). Although the

General discussion

163

organizations participating were matched on the percentage of ageing workers and job

tasks, it is probable that the non‐randomized design might be biased.

A clustered design was used to minimize data contamination46. To correct for the

clustered design within the dependency of observations (supervisor, workers and

repeated measurements of one worker), multilevel analyses were used in the

effectiveness study (chapter 7).

The external validity of the intervention may be questionable as the intervention was

tailored to highly educated workers in a hospital and university. Performance of the

intervention called for a certain degree of independence and autonomy in the work

situation and job performance. The results may therefore not to be generalizable to lower

educated workers, for example, in manufacturing jobs.

Non‐response bias

The loss to follow‐up during the intervention was 30% after 12 months. This is in line with

a recently published study which found that loss to follow‐up is a common problem

among workplace intervention studies47. Participation levels in health promotion

interventions at the workplace are typically below 50%. The workers lost after the

baseline measure in our study were lower educated, suffered more fatigue, had lower

work ability scores and reported lower scores on the self‐efficacy scale ‘willingness to

exert effort in completing behaviour’ and ‘willingness to initiate behaviour’ and possibly

more vulnerable to remain active in the labour market. To overcome selection bias, these

baseline differences between completers and non‐completers in the intervention‐ and

control group were taken into account during the analyses.

Implementation in other age groups

From the preventive point of view, sustainable employability should start at the beginning

of a worker’s career. Although our intervention has been developed based on the

determinants and needs of workers aged 45 years and older, it can be hypothesised the

intervention can be useful for all age groups. The tailored approach of the intervention

offers workers a tool to enhance their problem‐solving capacity as a technique that is not

limited to specific problems or age related situations. Therefore, in our opinion, workers

of all ages can benefit from our intervention programme. Whereas it is preferable to

implement the intervention more broadly, it is recommendable to re‐evaluate the

effectiveness of the intervention in all age groups.

Chapter 8

164

Measurements

A third issue concerns the quality of some of the measurements. In our studies about

determinants and adaptation strategies of sustainable employability we used both the

total work ability index score and the single‐item work ability questionnaire. The total

work ability index is partly based on the presence of a chronic health condition. Having

one or more chronic health conditions automatically resulted in a decreased work ability

score, which does not take into account the type and severity of the health condition. This

may give too much weight to chronic health conditions, resulting in work ability scores

that underestimate the worker’s true capability.

In addition, we assumed that the impact of a chronic health condition on work ability also

depends on the position and occupation. For example, pain in the joints (e.g. knee or

lower back pain) might have more impact on workers with a high physical workload such

as blue collar workers, while memory recall problems or problems with sustained

attention would have more impact on office workers. It is in this context that we used the

single‐item work ability score to determine the impact of the presence of a chronic health

condition on work ability and the impact of psychosocial and work‐related factors on this

association. Previous studies have shown that the single‐item work ability questionnaire

could be used instead of the total Work ability Index48‐50.

The measures of work conditions in our study – to determine the impact of those

conditions on the association between the presence of a chronic health condition and

work ability – were sector, occupation, duration function and shift work (chapter 4). We

did not focus on work characteristics such as autonomy, or physical or mental demands, as

used in other studies. Previous research findings showed that work conditions, varying

from role ambiguity, physical climate, work schedule, repetitive movements or ergonomic

conditions, predict work ability6. Our limited focus may have caused an underestimate of

the impact of work conditions of sustainable employability and might explain that we

found a very small impact of work conditions on work ability.

General discussion

165

RECOMMENDATION FOR RESEARCH

The following recommendations for future research can be made:

To improve the content of the intervention ‘Staying Healthy at Work’ it is

recommended to include a monitoring system to assist workers to set up a

structured action plan after the dialogue including well‐defined and realistic

goals, and the organization of peer‐group support for supervisors.

To evaluate the effect of the revised version of the intervention ‘Staying Healthy

at Work’ it is recommended to use a randomized controlled design in a sample of

the total work population and a follow‐up period of more than one year. In

addition, a cost‐benefit analysis should be performed to allow employers to draw

balanced conclusions regarding the overall value of the intervention.

A more detailed process evaluation may assist the interpretation of the findings

of an intervention study. Future research of the process evaluation of the

intervention ‘Staying Healthy at Work’ should be undertaken on both worker and

supervisor level, which considers: a) reasons for not participating in the study, b)

whether the failure to develop an action plan is due to the fact that no problems

or needs were identified or whether they were solved directly through dialogue,

c) whether solutions were realized at the time of the evaluation. In addition,

determining why workers successfully perform the intervention or withdraw on

different stages of the intervention is recommended.

If the intervention is proven effective, it is important to investigate the usability

and effectiveness of the intervention in different occupational groups (e.g. blue

collar or white collar workers).

RECOMMENDATIONS FOR PRACTICE AND POLICY

This thesis demonstrated the importance of a tailored approach with individual

adjustments necessary to increase sustainable employability. We recommended

interventions that provide an individual strategy to enhance sustainable

employability and that might have benefit for workers of all ages.

Supervisors have an important role in the process of enhancing sustainable

employability. They can support workers to reflect on the changeability of

problems and needs experienced and the feasibility of solutions, not by taking

over the responsibilities but strengthen the own responsibility of workers to

create a healthy and motivated work situation. Therefore, employers should

invest in the supervisors ability how to challenge the workers and to perform a

dialogue with the workers about sustainable employability.

Chapter 8

166

Different conceptualizations of ageing are interrelated and have different effects

on work related outcomes. Future policy to enhance sustainable employability

should include different conceptualizations of ageing like chronological,

functional and organizational ageing with regard to sustainable employability.

Differentiation in intervention programmes to enhance sustainable employability

for workers with and without a chronic health condition is not necessary.

Nevertheless, workers with a chronic health condition might benefit most from

such interventions and policies because they experience more problems, thus

have more needs, and in general reported lower scores on predictors of

sustainable work ability (e.g. work ability, work attitude, physical functioning).

We recommend special attention for these workers.

We recommend a company‐wide integrated approach which guarantees close

collaboration between workers, supervisors, and human resource management,

and ensures that workers have the tools, resources, training and opportunities

for development needed to fulfil their responsibility to prolong working life

successfully. This approach fits very well with the broadly accepted definition of

sustainable employability developed in 2010: ‘sustainable employment implies

that workers throughout their working life have real opportunities/ a set of

capabilities – and the necessary conditions – that allows them to achieve valuable

work functioning in current and future work with preservation of health and

welfare. This implies a work situation (task and context) that facilitates them, as

well as the attitude and motivation to exploit these opportunities’ 51.

The benefits of investing in interventions to enhance sustainable employability

will take some time to become apparent. Employers should thus see investment

in sustainable work participation as part of a good employment strategy and their

social responsibility in the long term.

General discussion

167

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s

Summary

Summary

173


social insurance systems, which are inextricably linked. Older workers are more vulnerable

in the labour process, because of vitality and ageing problems affecting their daily

performance and their ability to meet job competence requirements. Given the fact that

the prevalence of chronic health conditions generally increases with age, and that workers

will be required to work longer, the prevalence of chronic health conditions in the work

place can be expected to increase even further in the coming decades.

To maintain the level of welfare, the challenge is to keep the ageing workforce healthy

and productive for about a decade longer than the mean retirement practice of the past

period. To enhance sustainable employability of ageing workers, knowledge about the

determinants of such sustainability as well as the views of workers concerning continuing

work until retirement age is required to understand how they might overcome workplace

challenges and for the development of interventions to enhance sustainable

employability. An occupational intervention that aims to increase sustainable

employability should assist workers to solve problems associated with their working life,

giving them confidence in their ability to effectively carry out actions which ensure their


The main objectives of this thesis are 1) to provide insight into needs and determinants

regarding a sustainable working life among workers aged 45 years and older with and

without chronic health condition, and 2) to develop and evaluate an intervention aimed at

enhancing sustainable employability (chapter 1). The first objective is addressed in

chapters 2 to 5, and the second objective in chapter 6 and 7. In

Chapter 8, the results of this thesis are summarized and discussed.

Chapter 2 describes an in‐depth survey study of the number and type of experienced

problems due to ageing, obstacles to perform work tasks, retention factors to maintain

work and support needs to continue working life in the next years for ageing workers with

and without a chronic health condition. The study was carried out in 3,008 workers aged

45 years and older, working in nine different companies.

Thirty‐seven per cent (n = 1,109) of the workers self‐reported the presence of a chronic

health condition. Problems due to ageing were experienced by 42 % of the workers, and

26% of those workers reported obstacles to perform work. Retention factors were

reported by 82% of the workers, and 38% reported that they had special support needs if

they were to continue working over the coming years. Workers with a chronic health

condition experienced more problems due to ageing (56 vs 34 %; p <.001), more obstacles

Summary

174

(42 vs 16 %; p<.001) and more needs (51 vs 31 %; p<.001) compared to those without a

chronic health condition. The type of problems, obstacles, retention factors and support

needs were very similar, with problems mostly related to physiological and psychological

functioning (e.g. loss of energy level or problems with long‐lasting attention), and

retention factors and needs mostly related to work‐related factors (e.g. relation with

colleagues or task reduction). These findings suggest that interventions aimed to enhance

sustainable employability of ageing workers can be similar for persons with and without

chronic health conditions and should have a central focus on work‐related factors.

Chapter 3 presents the results of a cross‐sectional survey study of workers aged 45 years

and older to determine the relationship between chronological age, functional age and

work outcomes (n=2,983). Chronological age referred to the calendar age. Functional age

referred to a worker’s performance and was measured with questions about perceived

health status and the presence of a chronic health condition. Work outcomes were

experienced problems due to ageing, obstacles, retention factors, support needs to

continue working life and work ability.

Based on chronological age, workers in the age groups 50‐54 and 55‐59 years of age

reported significantly more problems due to ageing and more support needs to continue

working life in the next coming years compared to workers between 45‐49 years of age.

Workers aged 50 years and older experienced less facilitators and reported a decreased

work ability compared to the workers between 45‐49 years of age.

The association of chronological and functional age of workers aged 45 years and older on

work outcomes were significant but small, except for the presence of a chronic health

condition which was not related to chronological age. Older workers (60–64 years)

reported better scores on social functioning, mental health and vitality compared with

workers aged 45–59 years.

With respect to functional age, predominantly a chronic health condition was associated

with more problems, more barriers, more support needs and lower work ability scores.

The results suggested that employers can increase sustainable employability by taking the

physical and cognitive ability necessary to carry out the work into account, and not just

the calendar age.

Chapter 4 describes a cross‐sectional study to determine the influence of work conditions,


chronic health condition and work ability among workers aged 45 years and older. The

aforementioned dataset was extended with workers of telecommunication company

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175

(n=5,247). In addition, the variables associated with work ability for workers with and

without a chronic health condition were examined. This study showed that the presence

of a chronic health condition was negatively associated with work ability (B = ‐0.848). The

strength of this association slightly attenuated after subsequently adding individual

characteristics (B = ‐0.824), work conditions (B = ‐0.805) but more so after adding

psychosocial factors (B = ‐0.704) and especially perceived health variables (B = ‐0.049) to

the model. Variables associated with work ability for workers with and without a chronic

health condition were similar. Based on the lower mean scores for workers with a chronic

health condition on the work ability score as well for psychosocial factors and perceived

health, these workers might have the most benefit by a policy focussing on enhancing

those associated variables. Given these results, it may be a promising approach to address

perceived health as well as psychosocial factors in strategies and interventions towards a

sustainable healthy working life.

Chapter 5 examines the association of different coping styles with work ability among

workers aged 45 years and older, and if these association might depend on the extent of

job control and support (n=4,953). In addition, stratified analyses for differences in

associations between workers with and without a chronic health condition were

determined.

Active coping was positively associated with work ability (b=0.320; p<.001), whereas both

emotional and avoidance coping were negatively associated with work ability (b=‐0.243;

p<.001, b=‐0.363; p<.001 respectively). No interaction effect of job control and support

were found.

For workers with a chronic health condition, the association between active coping and

work ability was stronger, and job control had a small but positive effect on this

association. The negative association between the coping style expression of emotions

and work ability was stronger for workers without a chronic health condition. Emotional

support buffered the association between avoidance coping and work ability for workers

without a chronic health condition.

In today's society ‐with its dominance for self‐direction and its tendency to reframe

problems as challenges‐ the active coping style might be the most effective in the majority

of situations for workers aged 45 years and older. This seems especially true for workers

with a chronic health condition, and these workers can be further supported in their

adaptation by enhancing their job control.

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176

Chapter 6 describes the content of the intervention ‘Staying healthy at work’ and the

study design for evaluating the effectiveness of the intervention. The intervention aims to

enhance sustainable employability by increasing the workers’ problem‐solving capacity

and stimulating their awareness of their role and responsibility towards a healthy working

life.

The intervention comprised three stages: 1) the workers received a booklet focussed at

making an inventory of (work‐related) problems, needs, and career and personal

development opportunities. For these issues the worker was asked to assess the degree of

modifiability; 2) a dialogue between worker and supervisor to discuss solutions according

to a brainstorm format; and 3) making an action plan for the next year follow‐up period

for planning and implementing the solutions. The strategy of the intervention was to

change the workers awareness and behaviour by emphasizing their own decisive role in

attaining goals by giving them tools and support with which they can be effective in

carrying out the necessary actions. This may help them to learn that they can always

influence the impact of a situation by: (a) changing the situation by themselves; (b)

mobilizing the support of others; or (c) accepting the situation if it proofs to be

unchangeable. The intervention was incorporated into the annual appraisal procedure of

the organisations.

The supervisors in the intervention group were trained in taking the necessary actions by

means of stimulating self‐direction and enhancing knowledge and competencies. Workers

in the control group received business as usual; supervisors in the control group did not

participate in the training.

The primary outcome measures were vitality, work ability and productivity. The secondary

outcomes measures included fatigue, job strain, work attitude, self‐efficacy and work

engagement. Follow up measures were assessed after 3, and 12 months. A process

evaluation was conducted at both the supervisor and the worker levels, and satisfaction

with the content of the intervention was assessed.

Chapter 7 presents the effect evaluation of the problem‐solving based intervention

programme ‘Staying healthy at work’ compared to usual business within a quasi‐

experimental trial. Cluster randomisation on the level of the supervisor was used to avoid

contamination between workers.

The study included 236 workers from the University Medical Center Groningen (paediatric

and intensive care units) and the University of Groningen (technical services, secretarial

administrative services, financial economic affairs, human resource advice, facility services

and the library). The supervisors who agreed to participate were allocated in either the

Summary

177

intervention (n=12) or usual business group (n=7). Following the allocation of the

supervisors, the workers were divided to the intervention group (n = 129) or usual

business group (n = 107). After 12 months, data of 125 workers were available for the

analyses; 64 workers in the intervention group and 61 workers in the usual business group

respectively.

The problem‐solving intervention ‘Staying healthy at Work’ designed for workers to

enhance sustainable employability showed no superior effect on productivity and a

negative effect on work ability (B= ‐1.33, 95%CI ‐2.45 to ‐0.20) and vitality (OR=0.10,

95%CI 0.02‐0.46) compared to usual business. The secondary outcomes shows positive

effects for the scale perceived work attitude (B=5.29, 95%CI ‐9.59 to ‐0.99), the self‐

efficacy subscale persistence in the face of adversity (B = 1.45, 95%CI 0.42‐2.48) and the

subscale skill discretion of the psychosocial work characteristics (B = 1.78, 95%CI 0.74‐

2.83). No differences between the intervention and usual business group were found for

fatigue and work engagement.

In the process evaluation reported 43% of the workers (n=23) that the intervention had

increased their ability to clarify and explore problems with work participation and career

aspiration. About half of the workers reported to have become more capable in

conducting a dialogue with the supervisor about sustainable work participation (n=25;

46%) and to set up a structured action plan to improve work conditions after the

intervention (n=23; 44%). Fifty‐four per cent (n=29) of the workers stated that the

intervention had made them aware of the responsibility to create a healthy workplace,

and 37% reported that the intervention contributed to their self‐confidence in changing

the work situation for (n=20).

The conclusion of the intervention programme, whit its aim to encourage a self‐directed

cognitive behavioural process to enhance the workers’ problem solving capacity, is that

the intervention had no effect on productivity and a small but negative effect on work

ability and vitality. The positive results on the secondary outcomes and the results of the

process evaluation suggest that the intervention positively influenced the perspectives of

workers concerning their awareness and their feeling responsible for sustainable

employability.

Chapter 8, the general discussion, started with presenting the main findings in the light of

the study objective, followed by a discussion of methodological issues that should be

acknowledged when interpreting the findings.

Future research needs to develop a revised intervention including a monitoring system to

assist workers to set up a structured action plan after the dialogue including well‐defined

Summary

178

realistic goals, and the organization of peer‐group support for supervisors. Furthermore,

the effect of the intervention should be evaluated in a randomized controlled trial

representative for the total working population with a follow up of more than one year

and detailed process evaluation on both worker and supervisor level.

An important implication demonstrated in this thesis is that a tailored approach with

individual adjustments with attention to the different conceptualizations of ageing is

necessary to enhance sustainable employability, and that such a strategy might be useful

for workers of all ages. It is not necessary to differentiate for workers with and without a

chronic health condition in occupational intervention programmes regarding sustainable

employability and the benefits of interventions to enhance sustainable employable will

take time to become apparent. Moreover, an company‐wide integrated approach which

guarantees the close collaboration between workers, supervisors, and human resource

management, might ensure that workers have the tools, resources, training, and

opportunity for development needed to fulfil their responsibility to maintain and enhance

sustainable employable. Because individual agreements remains important to encourage


s

Samenvatting

Samenvatting

181

Door de hogere participatiegraad van oudere werknemers en de afname van de aanwas

van jongere werknemers door daling van het geboortecijfer (ontgroening) vergrijst de

beroepsbevolking. Om de productiviteit en daarmee het huidige welvaartniveau in onze

samenleving te behouden wordt van werknemers verwacht dat zij langer doorwerken.

Hierdoor worden werkgevers de komende jaren geconfronteerd met een

personeelsbestand waarin de oudere werknemer sterker is vertegenwoordigd dan

voorheen. De vergrijzing leidt eveneens tot aanzienlijke kostenstijging bij de

oudedagsregelingen en de gezondheidszorg, waarmee druk wordt gelegd op het sociale

zekerheidsstelsel. Door de toenemende participatie van oudere werknemers is de

aandacht voor de effecten van leeftijd en werk op zowel gezondheid als productiviteit

toegenomen. De maatschappelijke en wetenschappelijke uitdaging voor de komende

jaren is om de ouder wordende beroepsbevolking gezond, productief en duurzaam

inzetbaar te houden.

Gezondheid speelt een cruciale rol in het behouden van werknemers in het arbeidsproces.

Het aantal werknemers met chronische (gezondheids)klachten op de arbeidsmarkt zal

toenemen in de komende decennia, omdat de kans op het hebben van een chronische

aandoening toeneemt met de leeftijd. Diverse studies hebben aangetoond dat

gezondheidsproblemen een belangrijke reden vormen om het arbeidsproces vroegtijdig te

verlaten. Daarnaast heeft gezondheid ook een directe invloed op vitaliteit en op de

arbeidsproductiviteit. De impact van het ouder worden maakt het soms lastig om te

(blijven) voldoen aan de taken en eisen die worden gevraagd in het werk. Dit maakt de

ouder wordende werknemer kwetsbaarder in het arbeidsproces.

Kennis over hoe en wat werknemers nodig hebben om te kunnen blijven werken tot het

bereiken van de pensioengerechtigde leeftijd en de bepalende factoren die de duurzame

inzetbaarheid beïnvloeden is daarom gewenst. Deze kennis geeft inzicht in hoe oudere

werknemers omgaan met ervaren beperkingen op het werk en maakt het mogelijk om

interventies te ontwikkelen die bijdragen aan het vergroten van duurzame inzetbaarheid.

De doelstellingen van dit proefschrift, beschreven in hoofdstuk 1, zijn 1. inzicht te geven in

de ondersteuningsbehoeften voor werknemers van 45 jaar en ouder met en zonder een

chronische aandoening en factoren die van invloed zijn op hun duurzame inzetbaarheid en

2. het ontwikkelen en evalueren van een interventie om de duurzame inzetbaarheid van

werknemers te bevorderen. De resultaten met betrekking tot de eerste doelstelling

worden beschreven in de hoofdstukken 2 tot en met 5, de resultaten met betrekking tot

Samenvatting

182

de tweede doelstelling in de hoofdstukken 6 en 7. In hoofdstuk 8 volgen de conclusies en

worden de resultaten van de studies in dit proefschrift bediscussieerd.

In Hoofdstuk 2 wordt beschreven welke problemen werknemers ervaren in het werk door

het ouder worden en wat werknemers nodig hebben om het werk de komende jaren te

kunnen blijven uitvoeren. Hiervoor is een vragenlijstonderzoek uitgevoerd, waaraan meer

dan 3000 werknemers uit negen verschillende bedrijven hun medewerking verleenden. Er

is in de analyses onderscheid gemaakt tussen werknemers met en zonder een chronische

aandoening.

Zevenendertig procent (n=1109) heeft aangegeven een chronische aandoening te hebben.

Problemen door het ouder worden werd door 42% van de werknemers ervaren; 26% is

door deze problemen belemmerd bij het uitvoeren van het werk; 38% gaf aan

ondersteuning nodig te hebben om de komende jaren te kunnen blijven werken.

Werknemers met een chronische aandoening benoemden meer problemen door het

ouder worden (56% vs. 34%, p<.001), meer belemmerende factoren (42% vs. 16%, p<.001)

en hadden meer behoefte aan ondersteuning (51% vs. 31%, p<.001) in vergelijking met

werknemers zonder een chronische aandoening. De ervaren problemen bleken veelal

gerelateerd te zijn aan de fysieke en mentale gezondheid, zoals een verlaagd

energieniveau of problemen met langdurige concentratie. De ervaren ondersteunende

factoren en behoeften waren vooral gelegen in het werk, zoals de relatie met collega’s of

aanpassingen in het takenpakket. Er is geen aantoonbaar relevant verschil gevonden

tussen werknemers met en zonder een chronische aandoening.

De resultaten laten zien dat bij interventies ten behoeve van het bevorderen van

duurzame inzetbaarheid voor werknemers van 45 jaar en ouder geen onderscheid

gemaakt hoeft te worden tussen werknemers met en zonder chronische aandoening. Deze

interventies moeten zich vooral richten op werkgerelateerde factoren.

In hoofdstuk 3 wordt op basis van dezelfde vragenlijststudie de relatie tussen

chronologische leeftijd (kalenderleeftijd), functionele leeftijd (de eigen fysieke en

cognitieve vermogens om een functie goed te kunnen uitvoeren), ervaren problemen,

ondersteunende en belemmerende factoren, ondersteuningsbehoeften en werkvermogen

gepresenteerd. Functionele leeftijd is gemeten als ervaren gezondheid met subschalen

van de Rand36 en een vraag over de aanwezigheid van een chronische aandoening.

Werkvermogen is gemeten met de Work Ability Index.

Uit het onderzoek blijkt dat chronologische leeftijd samenhangt met ervaren gezondheid.

Werknemers in de leeftijdsgroepen van 50‐54 en 55‐59 jaar rapporteerden significant

Samenvatting

183

meer problemen door het ouder worden in vergelijking met werknemers in de

leeftijdsgroep van 45 tot 49 jaar. Werknemers van 50 jaar en ouder hebben een lagere

score op het werkvermogen en zij benoemden minder ervaren ondersteunende factoren.

Een samenhang tussen functionele leeftijd met ervaren problemen, ondersteunende en

belemmerende factoren, ondersteuningsbehoeften en het werkvermogen is aangetoond,

hoewel niet relevant. Significante samenhang werd alleen gevonden met de aanwezigheid

van een chronische aandoening (meer problemen, belemmerende factoren en

ondersteuningsbehoeften en een lager werkvermogen).

De resultaten laten zien dat werkgevers de duurzame inzetbaarheid van werknemers

kunnen vergroten door zich niet alleen te richten op chronologische leeftijd, maar vooral

de fysieke en cognitieve vermogens die nodig zijn om het werk uit te voeren in

beschouwing te nemen.

In Hoofdstuk 4 wordt beschreven in hoeverre er een samenhang bestaat tussen het

hebben van een chronische aandoening en het werkvermogen van werknemers van 45

jaar en ouder en welke persoons‐, werk‐, psychosociale‐ en gezondheidsgerelateerde

factoren deze samenhang beïnvloeden. De genoemde studiepopulatie is hierbij uitgebreid

met de werknemers van een groot telecommunicatiebedrijf, en betreft daarmee een

vragenlijstbestand van meer dan 5700 werknemers van 45 jaar en ouder.

De aanwezigheid van een chronische aandoening bleek negatief samen te hangen met het

werkvermogen (B=‐0,848). De toevoeging van de persoons‐, werk‐, en psychosociale

factoren aan het model beïnvloedden het verband (B=‐0,704), waarbij de toevoeging van

de variabelen over ervaren gezondheid de relatie tussen de aanwezigheid van een

chronische aandoening en het werkvermogen het sterkst bleek te beïnvloeden (B=‐0,049).

Een relevant verschil tussen variabelen die samenhangen met werkvermogen voor

werknemers met en zonder chronische aandoening is niet gevonden. Wel scoorden

werknemers met een chronische aandoening gemiddeld lager op het werkvermogen, de

psychosociale factoren en de ervaren gezondheid. Daarom is te verwachten dat een

interventie die zich richt op het verbeteren van deze factoren vooral voordeel oplevert

voor werknemers met een chronische aandoening.

De resultaten van deze studie laten zien dat het veelbelovend kan zijn om naast

gezondheid ook met name de psychosociale aspecten op te nemen bij interventies gericht

op het verbeteren van de duurzame inzetbaarheid van werknemers.

Hoofdstuk 5 presenteert de samenhang tussen verschillende manieren waarop

werknemers met problemen en stressoren omgaan (copingstijlen) en het werkvermogen.

Samenvatting

184

In de studie is gebruik gemaakt van vragenlijstonderzoek van de werknemers uit de tien

deelnemende organisaties waarvan de data over de uitkomstmaten in deze studie volledig

beschikbaar was (n=4953). Copingstijlen die worden onderscheiden in deze studie zijn

actief, emotioneel (ook wel passief) en vermijdend gedrag. Daarnaast is onderzocht of

deze samenhang wordt beïnvloed door een wisselwerking met de ervaren mate van

controle over het werk, en met emotionele en/of instrumentele steun.

Een actieve copingstijl bleek positief samen te hangen met het werkvermogen (B=0,320;

p<.001); emotioneel en vermijdend coping gedrag bleken negatief samen te hangen met

het werkvermogen (B=‐0,243; p<.001, B=‐0,363; p<.001). Deze samenhang is niet

afhankelijk van de mate van controle op het werk of de ervaren emotionele of

instrumentele steun. De samenhang tussen actieve coping en het werkvermogen bleek

sterker te zijn voor werknemers met een chronische aandoening; job control heeft een

kleine positieve invloed op deze samenhang. De negatieve samenhang tussen een

emotionele copingstijl en het werkvermogen bleek sterker aanwezig te zijn voor

werknemers zonder een chronische aandoening; voor deze groep geldt ook dat

emotionele steun een positief effect heeft op de negatieve samenhang tussen een

vermijdende copingstijl en werkvermogen.

De studie laat zien dat een actieve copingstijl in de huidige maatschappij – met een

verantwoordelijkheid van de werknemer om de eigen werksituatie actief te regisseren –

het meest effectief kan bijdragen aan het verbeteren van de duurzame inzetbaarheid van

werknemers van 45 jaar en ouder.

Hoofdstuk 6 beschrijft de ontwikkeling van de interventie 'Gezond aan het werk (blijven)'

en de opzet van het evaluatieonderzoek naar de effectiviteit van de interventie. Het is een

interventie met als doel het vergroten van het probleemoplossend vermogen van

werknemers. De interventiestrategie maakt werknemers bewust van de eigen rol en eigen

verantwoordelijkheid bij het creëren van een gezonde, motiverende en inspirerende

werksituatie. Leidinggevenden worden getraind om medewerkers te ondersteunen bij het

streven naar duurzame inzetbaarheid.

De interventie bestaat uit drie fasen: 1) een inventarisatie van ervaren (werk‐

gerelateerde) problemen, behoeften en persoonlijke ontwikkelingsmogelijkheden; 2) een

tweegesprek tussen werknemer en leidinggevende, waarin een brainstorm naar mogelijke

oplossingen plaatsvindt, en 3) het maken van een actieplan voor het komende jaar waarin

de werknemer specifieke oplossingen uitwerkt. Een stappenplan structureert het

doorlopen van de verschillende fasen van de interventie.

Samenvatting

185

De interventie biedt handvatten om werknemers te laten ervaren welke invloed zij zelf

kunnen hebben in het bereiken van doelstellingen of het ondernemen van acties om

inzetbaar te blijven. De interventie biedt ondersteuning bij het inschatten op welke wijze

verschillende situaties beïnvloedbaar zijn door: (a) het zelf veranderen van de situatie, (b)

ondersteuning van anderen te vragen, of (c) het aanvaarden dat een bepaalde situatie (op

dit moment) niet beïnvloedbaar is. De interventie kan worden opgenomen in de

bestaande gesprekscyclus tussen leidinggevende en medewerker zoals de

functioneringsgesprekken.

Vervolgens is een studie opgezet om de interventie uit te voeren in een testgroep en te

vergelijken met een controlegroep. Een dergelijke opzet maakt het mogelijk de

effectiviteit van de interventie te evalueren. De indeling in de interventie‐ of

controlegroep heeft plaatsgevonden op het niveau van de leidinggevende om te

voorkomen dat werknemers van één leidinggevende in zowel de controle‐ als de

interventiegroep terecht zouden komen. De primaire uitkomstmaten voor het meten van

de effectiviteit waren vitaliteit, het werkvermogen en de productiviteit. Daarnaast zijn als

secundaire uitkomstmaten vermoeidheid, de sociale en psychologische aspecten van werk

(taakeisen en regelmogelijkheden), de houding ten aanzien van werk, de eigen effectiviteit

en bevlogenheid gemeten. Vervolgmetingen vonden plaats na 3 en 12 maanden. Een

procesevaluatie is uitgevoerd op het niveau van de leidinggevende en de werknemer.

De resultaten van de effectstudie, uitgevoerd bij medewerkers van het Universitair

Medisch Centrum Groningen (kindergeneeskunde en diverse intensive care afdelingen) en

de Rijksuniversiteit Groningen (technische dienstverlening, secretariële/administratieve

diensten, financieel economische zaken, human resource advies, facilitaire diensten en de

bibliotheek), worden gepresenteerd in Hoofdstuk 7. De leidinggevenden die ingestemd

hadden met deelname werden op basis van instemming met deelname toegewezen aan

de interventie (n =12) of de controle groep (n=7). De leidinggevenden in de

interventiegroep ontvingen een training, de leidinggevenden in de controlegroep niet. De

deelnemende medewerkers werden, afhankelijk van hun leidinggevenden, toegewezen

aan de interventie (n = 129) of controlegroep (n = 107). De medewerkers in de

interventiegroep doorliepen alle fasen van de interventie; de werkwijze voor werknemers

in de controlegroep bleef ongewijzigd.

Van 125 werknemers waren na 12 maanden gegevens beschikbaar voor het meten van de

effectiviteit; 64 werknemers in de interventiegroep en 61 werknemers in de

controlegroep. Er is geen effect gevonden ten aanzien van productiviteit; wel was er een

Samenvatting

186

negatief effect op werkvermogen (B= ‐1,33; 95% BI ‐2,45 tot ‐0,20) en vitaliteit (OR=0.10;

95% BI 0,02‐0,46).

De secundaire uitkomstmaten lieten positieve effecten zien voor de ‘houding ten aanzien

van werk’ (B=5.29; 95% BI ‐9,59 tot ‐0,99), de subschaal ‘doorzetten bij tegenslagen’ van

de uitkomstmaat eigen effectiviteit (B=1.45; 95% BI 0,42‐2,48) en de subschaal ‘skill

discretion’ ‐in hoeverre medewerkers het gevoel hebben dat hun expertise wordt benut

binnen de organisatie en de mate waarin medewerkers het gevoel hebben nieuwe dingen

te leren binnen hun werk‐ van de sociale en psychologische aspecten van werk (B = 1.78;

95% BI 0,74‐2,83). Er is geen effect gevonden op vermoeidheid en bevlogenheid.

In de procesevaluatie rapporteerde 43% van de werknemers (n=23) door de interventie

beter in staat te zijn om ontwikkelingsbehoeften en knelpunten te benoemen. Ruim 40%

van de werknemers gaf aan na afloop van de interventie beter in staat te zijn een

tweegesprek over duurzame inzetbaarheid te voeren met de leidinggevende (n=25; 46%)

en een gestructureerd plan van aanpak op te zetten voor het verbeteren van de eigen

werksituatie (n=23; 44%). Vierenvijftig procent (n=29) van de werknemers gaf aan dat zij

door de interventie meer bewust waren van de eigen invloed op een gezonde en

motiverende werkomgeving en werksituatie; 37% vond dat het zelfvertrouwen om

veranderingen in de werksituatie tot stand te brengen was verbeterd (n=20).

De onverwachte negatieve resultaten kunnen worden veroorzaakt door keuzes die zijn

gemaakt tijdens de implementatie van de interventie in de praktijk en de wijze waarop de

diverse stappen van de interventie zijn uitgevoerd op het niveau van zowel medewerkers

als leidinggevenden. Ook de korte follow‐up periode en het feit dat onduidelijk is in

hoeverre duurzame inzetbaarheid al wordt besproken op de afdeling kunnen bijdragen

aan de negatieve resultaten op de hoofduitkomstmaten. Succesvolle elementen van de

oplossingsgerichte interventie betreffen het gegeven dat werknemers op korte termijn

anders tegen hun werk aankijken en dat werknemers zich meer bewust zijn van hun eigen

kunnen en eigen verantwoordelijkheid om inzetbaar te blijven. In hoeverre deze

interventie op de langere termijn ‐anders dan uit onze eerste resultaten blijkt‐ positief

bijdraagt aan de uitkomstmaten van duurzame inzetbaarheid dient nader onderzocht te

worden.

In hoofdstuk 8 zijn de belangrijkste resultaten van dit proefschrift samengevat en

bediscussieerd. De sterke kanten, methodologische overwegingen en beperkingen zijn

besproken. Tenslotte zijn aanbevelingen gedaan voor toekomstig onderzoek en voor

duurzame inzetbaarheid in beleid en de praktijk.

Samenvatting

187

Toekomstig onderzoek is nodig om een aantal stappen van de interventie nader uit te

werken, zoals bijvoorbeeld een monitoringsysteem om werknemers te ondersteunen bij

het opzetten van een gestructureerd actieplan met goed gedefinieerde en realistische

doelen na afloop van het tweegesprek. De organisatie van intervisiebijeenkomsten voor

leidinggevenden kan bijdragen aan de uitwisseling en het vergroten van de kennis over

hoe en op welke wijze leidinggevenden oplossingsgerichte ondersteuning kunnen bieden

aan werknemers. Tevens wordt aanbevolen om het effect van de interventie nogmaals te

evalueren in een gerandomiseerd onderzoek onder een representatieve groep

werknemers qua leeftijd en bedrijfssector. Hierbij is het wenselijk om de effectiviteit over

een periode van langer dan 12 maanden te meten en een gedetailleerde procesevaluatie

uit te voeren op het niveau van de werknemer en leidinggevende.

Het maken van onderscheid tussen werknemers met en zonder chronische aandoening is

niet nodig om te werken aan duurzame inzetbaarheid. Het is te verwachten dat een

organisatiebrede integrale aanpak, voor alle werknemers ongeacht leeftijd en in nauwe

samenwerking met werknemers, leidinggevenden en strategisch personeelsmanagement,

werknemers de middelen, (hulp)bronnen, opleiding en ontwikkelingskansen biedt die

nodig zijn om zelfstandig hun duurzame inzetbaarheid te verbeteren. Bij het streven naar

duurzame inzetbaarheid blijft maatwerk belangrijk.

R

Research Institute for Health Research SHARE


191

This thesis is published within the Research Institute SHARE of the Graduate School of

Medical Sciences (embedded in the University Medical Center Groningen / University of

Groningen). Further information regarding the institute and its research can be obtained

from our internetsite: www.rug.nl/share.

More recent theses can be found in the list below.

((co‐) supervisors are between brackets)

2013

Pitel L. Sociocultural determinants, gender and health‐related behaviour in

adolescence (prof SA Reijneveld, dr JP van Dijk, dr A Madarasova‐Geckova)

Majerníková M. Sef‐rated health and mortality after kidney transplantation

(prof JW Groothoff, dr JP van Dijk, dr J Rosenberger, dr R Roland)

Verschuren J. Sexuality and limb amputation: perspectives of patients,

partners and professionals (prof JHB Geertzen, prof PU Dijkstra, prof P Enzlin)

Riphagen‐Dalhuisen J. Influenza vaccination of health care workers

(prof E Hak)

Hasselt FM van. Improving the physical health of people with severe mental

illness; the need for tailor made care and uniform evaluation of interventions

(prof AJM Loonen, prof MJ Postma, dr MJT Oud, dr PFM Krabbe)

Piening S. Communicating risk effectively

(prof FM Haaijer‐Ruskamp, prof PA de Graeff, dr PGM Mol, dr SMJM Straus)

Siebelink MJ. The child as a donor; a multidisciplinary approach

(prof HBM van de Wiel, prof PF Roodbol)

Sidorenkov G. Predictive value of treatment quality indicators on outcomes in

patients with diabetes (prof FM Haaijer‐Ruskamp, prof D de Zeeuw)


192

Vu DH. Clinical pharmacology of tuberculosis drugs and tuberculosis control

in developing world; the involvement of private pharmacy and the

individualization of treatment using dried blood spot (prof JRBJ Brouwers,

prof DRA Uges, prof VH Le, prof DH Nguyen, dr JWC Alffenaar)

Sijtsma A. Physical activity and overweight in young children

(prof PJJ Sauer, prof RP Stolk, dr E Corpeleijn)

Rosicova K. Regional mortality in Slovakia: socioeconomic indicators and

ethnicity (prof JW Groothoff, dr JP van Dijk, dr A Madarasova‐Geckova)

Bobakova D. Youth subcultures and problem behaviours in Slovakia: hip‐hop,

techno‐scene, metal, punk, skinheads and Roma

(prof SA Reijneveld, dr JP van Dijk, dr A Madarasova‐Geckova)

Arends I. Prevention of recurrent sickness absence in workers with common

mental disorders (prof JJL van der Klink, prof U Bültmann)

Theunissen MHC. The early detection of psychosocial problems in children

aged 0 to 6 years by Dutch preventive child healthcare; professionals and

their tools (prof SA Reijneveld, dr AGC Vogels)

Bragaru M. Sports and amputation

(prof JHB Geertzen, prof PU Dijkstra, dr R Dekker)

Broesamle TC. Designing health care services using systems thinking; a

theory, a method and their application in the Dutch community pharmacy

(prof JJ de Gier, prof JJ van der Werf)

Jong J de. Antibiotics use in children; pharmacoepidemiological, practical and

environmental perpectives in the Netherlands (prof LTW de Jong‐van den

Berg, dr TW de Vries)

Rettke HG & Geschwindner HM. Long‐term outcomes in stroke rehabilitation

patients and informal caregivers (prof WJA van den Heuvel)


193

Fortington LV. Enabling the elderly person with lower limb amputation

through surgery,rehabilitation and long term care (prof JHB Geertzen, prof

PU Dijkstra, dr GM Rommers)

Lako IM. Depressive symptoms in patients with schizophrenia; count

symptoms that count (prof K Taxis, prof D Wiersma)

Arnardottir AH. Regulatory benefit‐risk assessment; different perspectives

(prof FM Haaijer‐Ruskamp, prof PA de Graeff, dr PGM Mol, SMJM Straus)

Meijer A. The forest through the trees; investigating depression in patients

with cancer and patients with myocardial infarction using systematic reviews

and meta‐analytic techniques (prof P de Jonge, dr HJ Conradi, dr BD Thombs)

Kuchenbecker WKH. Obesity and female infertility

(prof JA Land, prof BHR Wolffenbuttel, dr A Hoek, dr H Groen)

Rozenbaum MH. Costs and effectiveness of extended vaccination strategies

against pertussis and pneumococcal disease (prof MJ Postma, prof E Hak)

Kingma EM. Intelligence and functional somatic symptoms and syndromes

(prof JGM Rosmalen, prof J Ormel, prof P de Jonge)

Kedde JH. Sexual health of people with disability and chronic illness

(prof HBM van de Wiel, prof WCM Weijmar Schultz)

Horst PGJ ter. Clinical pharmacology of antidepressants during pregnancy

(prof B Wilffert, prof LTW de Jong‐van den Berg)

Sinha R. Adjustment to amputation and artificial limg, and quality of life in

lower limb amputees (prof WJA van den Heuvel, prof P Arokiasamy, dr JP van

Dijk)


194

2012

Pechlivanoglou P. Applying and extending mixed‐effects models in health in

health economics and outcomes research (prof MP Postma, prof JE Wieringa,

dr HH Le)

Verboom CE. Depression and role functioning; their relation during

adolescence and adulthood (prof J Ormel, prof WA Nolen, prof BWJH

Penninx, dr JJ Sijtsema)

Benka J. Living with rheumatoid arthritis: do personal and social resources

make a difference? (prof JW Groothoff, prof JJL van der Klink, dr JP van Dijk,

dr I Rajnicova‐Nagyova)

Kalina O. Sexual risky behaviour among Slovak adolescents and young adults;

social and psychological factors (prof SA Reijneveld, dr JP van Dijk, dr A

Madarasova‐Geckova)

Crijns HJMJ. Drug related safety issues affecting pregnancy outcome and

concerning risk minimisation measures; emphasis on pregnancy prevention

programmes (prof LTW de Jong‐van den Berg, dr SMJM Straus)

Vries HJ de. Working with pain; sustainable work participation of workers

with chronic non‐specific musculoskeletal pain (prof JHB Geertzen, prof JW

Groothoff, prof MF Reneman, dr S Brouwer)

Karsten J. On the threshold of disorder; definition and course of subthreshold

depression and subthreshold anxiety (prof WA Nolen, prof BWJH Penninx, dr

CA Hartman)

Abma FI. Work functioning: development and evaluation of a measurement

tool (prof JJL van der Klink, prof U Bültmann)

For more 2012 and earlier SHARE‐theses see our website.

D

Dankwoord

Dankwoord

197

Vanuit de praktijk st(r)oomde ik de wetenschappelijke wereld binnen vanwege mijn interesse

in onderzoek en startte ik het voorliggend promotieonderzoek. Ik verkeerde in de

veronderstelling dit onderzoek zelfstandig en ruimschoots binnen de 4 jaar af te kunnen

ronden. Inmiddels ben ik deze en andere illusies armer, maar gelukkig vele ervaringen rijker. Bij

een promotieonderzoek zijn meer mensen betrokken dan verwacht, waarbij ieder op eigen

wijze heeft bijgedragen tot de realisatie van dit proefschrift . Dat ik mijn promotietraject als

een zeer plezierige uitdaging heb ervaren vol mogelijkheden en kansen, komt juist door de

samenwerking met de vele betrokkenen. Mijn proefschrift zou dan ook niet compleet zijn

zonder dit dankwoord.

Een speciaal woord van dank gaat uit naar de verschillende bedrijven die hebben deelgenomen

aan de studies. Met name de mensen die zich sterk hebben gemaakt voor de introductie van

mijn onderzoek binnen hun organisatie en de deelnemende medewerkers wil ik van harte

bedanken. Jullie waren het die de toch behoorlijk uitgebreide vragenlijsten hebben ingevuld of

deel hebben genomen aan de interventiestudie. Bedankt, voor de openheid en het vertrouwen

waarmee velen mij als onderzoeker hebben ontvangen. Zonder jullie vrijwillige medewerking

was de uitvoering van mijn project niet mogelijk geweest. Bedankt voor jullie bijdrage aan de

nieuwe kennis en inzichten over duurzame inzetbaarheid!

In het bijzonder wil ik ook mijn promotoren Prof. dr. Jac van der Klink en Prof. dr. Johan

Groothoff en copromotor dr. Sandra Brouwer bedanken.

Beste Jac, dank voor het verrijken van ons projectteam als eerste promotor. Een lopend

onderzoek overnemen is niet eenvoudig, maar je expertise en ervaring binnen de

bedrijfsgezondheidszorg is een welkome aanvulling geweest in ons team en heeft veel

bijgedragen bij de ontwikkeling en implementatie van de interventie. De wijze waarop jij kennis

presenteert en overdraagt – rustig, correct en altijd met een positieve klank ‐ is zeer

inspirerend.

Beste Johan, met veel plezier denk ik terug aan onze uitjes naar de diverse bedrijven die we

benaderden voor medewerking aan ons project. De openhartige en olijke manier waarop jij

een gesprek de juiste kant op weet te draaien, maar met een duidelijke serieuze boodschap, is

prachtig. Daarnaast mijn verwondering over je snelle respons, de directe en positieve wijze

waarop je communiceert en de inspiratie die onze gesprekken opleverde. Met je inzetbaarheid

en enthousiasme ben je een voorbeeld voor mijn doelgroep.

Beste Sandra, dank voor het enthousiasme, je deskundigheid en de stimulans die ik door de

jaren heen heb mogen ontvangen. Je altijd daadkrachtige ondersteuning en scherpzinnigheid

zijn erg waardevol geweest bij het uitvoeren van dit project. Vaak hebben je opmerkingen mij

aan het denken gezet en leidde dit tot nieuwe inzichten. Daarnaast ben je gedurende mijn

onderzoektraject een voortreffelijke begeleider en ook een goede opleider tot onderzoeker

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gebleken, met oog voor nevenzaken die misschien nog wel belangrijker waren. Je deur stond

altijd open voor vragen of een goed gesprek en je zorg voor mijn gezondheid in de periode dat

mijn eigen inzetbaarheid het even liet afweten heb ik zeer gewaardeerd. Ik zie dan ook uit naar

onze samenwerking in de toekomst.

Dr. Boudien Krol wil ik graag bedanken voor haar rol als copromotor in de eerste jaren van het

project. Beste Boudien, de precisie waarmee jij als zeer gedreven onderzoeker werkt liet mij al

snel inzien wat wetenschap inhoudt. Je hebt mij getoond hoe belangrijk goede communicatie is

en ik waardeer het zeer op welke wijze je mij de vrijheid hebt gegeven om het onderliggende

project op te zetten. Je betrokkenheid bij zowel het project als bij mij als persoon was zeer

motiverend. Fantastisch dat er zo’n mooie nieuwe uitdaging op je pad kwam en wat fijn dat

onze wegen elkaar nog regelmatig kruisen. Dank voor de leerzame samenwerking.

Ik wil jullie graag allen danken voor het teamwork en het gestelde vertrouwen in mij

gedurende het project. Van iedereen heb ik jullie expertise, manier van aanpak en nog vele

andere zaken kunnen ‘afkijken’, die mij in de afgelopen jaren hebben gevormd tot

onderzoeker.

Ik dank de leden van de leescommissie prof. dr. ing. Lex Burdorf, prof. dr. Frank van Dijk en

prof. dr. Michiel Reneman voor het beoordelen van dit proefschrift.

De leden van de begeleidingscommissie, dr. Angela de Boer, drs. Jaap Bruins Slot, prof. dr. ing.

Lex Burdorf en dr. Bas Sorgdrager ben ik dankbaar voor de geschonken tijd en aandacht aan

mijn onderzoek. De bijeenkomsten waren zeer constructief en de balans tussen wetenschap en

praktijk werd grondig bediscussieerd en afgewogen. Na de bijeenkomsten zat ik altijd vol

plannen en nieuwe ideeën, alleen heeft het wel eens aan tijd ontbroken om deze allemaal tot

uitvoer te brengen. Jullie toegankelijkheid, binnen en buiten de bijeenkomsten, heb ik als zeer

bijzonder ervaren.

Suzanne Matthijssen en Hanneke Vervoort wil ik graag bedanken voor het uitzetten van de

vragenlijsten en verwerken van de data. Voor mij was het een leerzaam traject om jullie te

mogen begeleiden. Dank voor de prettige samenwerking.

Tijdens mijn project heb ik vele mensen leren kennen en gemerkt dat je als onderzoeker van

alle markten thuis moet zijn (is ook een belangrijke competentie…). Het was erg prettig om op

sommige punten ondersteuning te mogen ontvangen van de experts. Het gaat mij niet lukken

om iedereen hier persoonlijk te bedanken, maar ik wil graag laten weten dat ik ontzettend veel

heb mogen leren van de (veelal) HRM‐ers en medewerkers vanuit de bedrijfsgezondheidszorg,

die als aanspreekpunt fungeerden binnen de deelnemende bedrijven. Het was als onderzoeker

prettig om via jullie de ins en outs van de organisatie door te spreken, wat mij erg heeft

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geholpen om mijn onderzoek zodanig uit te voeren dat dit aansloot bij de praktijk. Deze

informatie helpt mij nog steeds om de praktijk niet uit het oog te verliezen bij het uitvoeren

van wetenschappelijke onderzoek.

Mijn collega’s op de 6e verdieping, waarvan sommigen ondertussen zijn uitgevlogen naar de 4e,

7e of elders, wil ik graag bedanken voor de plezierige contacten. We hebben heel wat te

bespreken gehad, al dan niet gerelateerd aan werk. Ook voor ‘tips and tricks’ stond er altijd wel

een deur open. Graag wil ik nog een aantal mensen in het bijzonder noemen. Michiel de Boer,

je kritische vragen en de verhelderende uitleg hebben mij zeer geholpen om te komen tot het

resultaat dat er nu ligt. Het is bewonderenswaardig hoe je de voor mij ingewikkelde

methodologische analyses kunt omzetten in praktische taal. Het is dan ook zeer plezierig om

ook in het vervolgproject methodologisch ondersteuning van je te mogen ontvangen. Roy

Stewart, dank voor de vragen die ik in de beginperiode bij je heb kunnen neerleggen met

betrekking tot powerberekeningen en mulitlevel analyses. Lida op ‘t Ende en Janneke Vos wil ik

graag danken voor hun ondersteuning bij het maken en inplannen van diverse afspraken. Het is

geen gemakkelijke klus om al die agenda’s te stroomlijnen, maar er werd altijd een plekje

gevonden of anders wel gecreëerd.

Iris Arends, Femke Abma en Haitze de Vries, erg leuk om met jullie te brainstormen over

toekomstmogelijkheden als postdocs. Ik hoop dat we er iets moois van kunnen maken! Ute

Bultmann, als overbuurvrouw stond je deur altijd open voor vragen. Ik zie uit naar onze

toekomstige samenwerking. Hardy van de Ven, onze samenwerking geeft mij nieuwe inzichten

en de feedbackmomenten zijn erg waardevol voor mij. Karin Veldman, ik hoop dat we in het

komende jaar weer gezellig gaan sporten want ik mis onze inspirerende gesprekken. Danielle

Jansen, dank voor de fijne gesprekken. Andrea Fokkens en Merlijne Jaspers, dank voor jullie

zorgzame opvang toen ik als kersverse promovendus op de afdeling neerstreek. Manna Alma,

Leenke Visser en Annemieke Luinge, bedankt voor jullie gezelligheid. En zeker ook niet te

vergeten de verschillende externe promovendi, die altijd bereid waren om vanuit hun eigen

invalshoek mee te denken naar oplossingen. Dank voor de interessante gesprekken.

Speciaal wil ik graag mijn kamergenoten Margriet Hielkema en Anja Holwerda bedanken voor

de vele gezellige momenten, de thee en niet te vergeten het plezier wat maakt dat een

werkplek motiverend is. Het bijeen plaatsen van drie zo totaal verschillende persoonlijkheden

is eigenlijk een klein sociologisch project. Kunnen we vanuit een psychologische invalshoek het

succes verklaren? Of is de demografische overeenkomst de verklarende variabele? Wat het

resultaat ook mag zijn, ik heb in ieder geval een hele goede tijd met jullie als kamergenoten

mogen beleven. Dank voor jullie zorg en steun die er altijd was. Ik hoop dat ik nog een tijdje

van jullie gezelligheid kan genieten.

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De collega’s van de RUG, het UMCG en de Hanzehogeschool Groningen die ik in de loop der

jaren heb leren kennen ‐ al dan niet door het werk ‐ en waar ik geregeld langs kon komen voor

het delen van visies, de impact van de (bestuurlijke en politieke) wijzigingen in de zorg of

gewoon een praatje wil ik graag bedanken voor hun betrokkenheid bij mijn werkzaamheden en

mij als persoon. Het is fijn om af en toe even vanuit een ander perspectief en een andere blik

naar bepaalde zaken te kijken. Dat heeft op mij altijd een zeer verfrissende werking gehad.

Het LUMC, met name Jan Maasen en Vivianne de Croon‐Koevoets, wil ik graag danken voor de

geboden mogelijkheid om de effectiviteit van de in dit proefschrift beschreven interventie te

kunnen onderzoeken in een vervolgstudie.

Vrienden en (schoon)familie, jullie geduld is gedurende dit traject (te) vaak op de proef gesteld

door het uitstellen van telefoontjes en afspraken. Manon Post, heerlijk dat ik altijd op je kan

rekenen als dat nodig. Karin Top‐Meijerink, je hebt mij laten zien hoe waardevol het leven is.

Het is erg verdrietig dat je niet meer onder ons bent. Onze fijne gesprekken, je optimisme en

je lach zette de ervaren werkdruk altijd in een ander perspectief. Sharon Haarmans en

Annemiek Rutte, door jullie ben ik uiteindelijk in het onderzoek gerold. Ik hoop dat we als VOD‐

jes snel weer eens bijeenkomen. Hoewel ik graag iedereen persoonlijk zou noemen die in de

afgelopen jaren om de één of andere reden voor mij belangrijk is geweest, zie ik in dat dit echt

niet gaat lukken. Weet dat ik jullie allen ontzettend dankbaar ben voor jullie steun en begrip. Ik

hoop dat ik nog lang van jullie onvoorwaardelijke vriendschap mag blijven genieten. Nu mijn

proefschrift is afgerond beloof ik beterschap!

Tot slot mijn trainingsmaatjes op de atletiekbaan, jullie wil ik graag bedanken voor de

betrokkenheid bij mijn werk, maar nog meer de afleiding en ontspanning die jullie mij

brachten. De plezierige omgeving heeft mij altijd rust en creativiteit gegeven.

Lieve pap en mam, jullie wil ik graag bedanken voor alle mogelijkheden en vrijheid die jullie mij

hebben gegeven om te doen en te laten wat ik wil. Dankzij jullie ben ik geworden wie ik ben en

kan ik zijn wie ik ben. Dank voor alle liefde en steun.

Cindy en Ruud, jullie zijn mijn allerliefste zus en allerliefste broer(tje). Het is voor mij speciaal

dat jullie mijn paranimfen willen zijn. Cindy, Pieter en Eric, bedankt voor alle overnachtingen

wanneer ik weer eens ver van huis moest zijn.

Lieve Kim, je komst, je vrolijkheid, je frisse en verwonderde blik op de wereld is veel meer

waard dan dit boek met letters. Er is niet mooiers dan met jou en je lieve papa samen te zijn.

Lieve Eddy, bedankt voor je liefde, vertrouwen, geduld en vooral onvoorwaardelijke steun.

Door de rust die je mij gaf, is jouw bijdrage aan dit proefschrift veel groter dan je denkt. Dankzij

jou is het gelukt; je bent erg bijzonder voor mij!

cv

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Wendy Koolhaas is op 5 januari 1980 geboren in de Noordoostpolder. In 2007 begon zij

aan het promotietraject ‘duurzame inzetbaarheid van oudere werknemers’ op de afdeling

sociale geneeskunde, sectie arbeid en gezondheid, van het Universitair Medisch Centrum

Groningen. Binnen dit onderzoek beschreef zij welke problemen werknemers van 45 jaar

en ouder ervaren in het werk, wat zij nodig hebben om te blijven werken, welke factoren

invloed zijn op hun duurzame inzetbaarheid. Deze informatie is gebruikt om een

interventie te ontwikkelen gericht op het vergroten van de inzetbaarheid van

werknemers. De resultaten van dit onderzoek staan beschreven in dit proefschrift.

Naast haar promotietraject heeft Wendy meegewerkt aan diverse andere

onderzoeksprojecten op het gebied van duurzame inzetbaarheid, zoals het rapport

‘Duurzame inzetbaarheid van de oudere werknemer: stand van zaken’ en de ‘Handreiking

duurzame inzetbaarheid voor oudere werknemers, een integrale benadering voor

organisaties’. Tevens is zij betrokken bij het project ‘Shift Your Work’, met aandacht voor

de voorwaarden van duurzame inzetbaarheid van werknemers met onregelmatige

diensten, nacht‐ en ploegendiensten. Als vervolg op haar promotietraject heeft Wendy de

door haar ontwikkelde interventie ‘Oplossingsgericht werken aan Duurzame

Inzetbaarheid’ geïntroduceerd op een aantal afdelingen van het Leids Universitair Medisch

Centrum, ter bepaling van de effectiviteit.

Voor de start ging met haar promotieproject volgde zij de opleiding Medisch

Beeldvormende en Radiotherapeutische Technieken aan de Hanzehogeschool van

Groningen, afgerond met een adviesrapport voor het Sport Medisch Centrum Groningen

over “Botscan, de betekenis bij sportindicaties”. Omdat wetenschappelijk onderzoek haar

aansprak is zij daarna sociologie gaan studeren, waarbij de focus op arbeid lag. Deze

studie werd afgerond met een stage bij het Centrum voor Arbeid en Beleid (CAB) te

Groningen. Hier heeft zij onderzoek uitgevoerd naar implementatieverschillen tussen

gemeenten in Noord‐Nederland bij de invoering van de Wet Werk en Bijstand en de

invloed van externe factoren op de beleidskeuzes van gemeenten, resulterend in een

scriptie. Tijdens haar opleidingen is zij parttime werkzaam geweest als radiodiagnostisch

laborant in het Martini Ziekenhuis te Groningen. Hierna is zij gaan werken op de afdeling

Nucleaire Geneeskunde van het Universitair Medisch Centrum Groningen, waar zij haar

kennis vanuit beide opleidingen kon combineren. Naast de patiëntenzorg heeft zij

onderzoek verricht naar een minder belastende onderzoeksmethode voor patiënten om

osteoporose vast te stellen.

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204

PHD PORTFOLIO SUMMARY

Research techniques Applied longitudinal data analysis Groningen, July 2012 Multi‐level analyses Maastricht, November 2008 Regression Analysis Rotterdam, August 2008 Medical Statistics Groningen, June 2008 Introduction Multi‐level analyses Groningen, January 2008 General research competences Science Writing January – September 2009 Project Management for Scientific Research Groningen, 2007‐2009 Publishing in English Groningen, September – December 2008

Presenting in English Groningen, June – September 2008 Reference Manager Groningen, February – March 2007 Depth and breadth of knowledge Intensieve taaltraining Engels Vught, May 2013 Career orientation for PhD students and scientific employees

Groningen, January – March 2013

Master class Public Health Research in Practice: how to develop effective interventions in public health practice

Wageningen, October 2012

Development and teacher training how to use the problem‐solving method in the dialogue about sustainable employability (for supervisors)

Groningen, 2009 Papendal, May 2010 Leiden, 2011‐2012

Supervising student , research employee, and PhD Groningen, 2010 ‐ present Tutoring medical students Groningen, 2007 ‐ 2009 Working with small groups Groningen, August 2007 Scientific international presentations International Conference on ‘Work, Well‐being and Wealth: Active ageing at Work’. Oral: Effectiveness of the ‘Staying Healthy at work intervention’. Poster: Chronic health conditions and work ability in the ageing workforce: the impact of work conditions, psychosocial factors and perceived health.

Helsinki, August 2013

EUPHA 5th annual European public health conference ‘All Inclusive

Public Health’. Oral: Effectiveness of a problem solving intervention for workers to promote sustainable employability. Oral presentations: abstracts. Eur J Public Health 2012; 22 (supplement 2), 28‐28.

Malta, November 2012

WDPI 2nd Scientific Conference on Work Disability Prevention and

Integration ‘Healthy ageing in a working society’. Poster: Chronic health conditions and work ability in the ageing work force: the impact of work conditions and psychosocial factors.

Groningen, October 2012

WDPI 1st Scientific Conference on Work Disability Prevention and

Integration. Oral: The impact of ageing problems, a chronic health condition, and type of occupation on a sustainable healthy working life.

Angers, September 2010

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205

ICOH‐WOPS 4th International Conference on Psychosocial Factors of Work. Oral: Enhancing a sustainable healthy working life of older workers with a chronic disease. Poster: The workers' perspectives to enhance sustainable working life.

Amsterdam, June 2010

Expert meeting scientific network Work Ability Index. Oral: Towards a sustainable healthy working life. Results of a cross sectional study and development of an intervention.

Rotterdam, February, 2010

IV International Congress of Disability Management. Oral: Enhancing work participation of the older employee with a chronic disease.

Berlin, September 2008

National presentations VCD Humannet Oral: Hoe houden we mensen langer gezond aan het werk. Wat werkt voor de ‘oudere’ werknemer?

Oegstgeest, October 2013

Nascholing NVAB Kring Noord ’Healthy Ageing at Work’. Oral: Wat werkt voor de oudere werknemers? Hoe houden we mensen langer gezond aan het werk.

Groningen, April 2013

Nascholing NVAB‐Noord. Oral: Gezond aan het werk (blijven)! Resultaten en implementatie.

Haren, June 2010

Expertmeeting HRM professionals NFU/ SoFoKLES. Oral: Gezond aan het werk (blijven)! Resultaten en implementatie.

Utrecht, May 2010

Bedrijfsgeneeskundige dagen, VNAB Workshop: Oplossingsgericht werken aan duurzame inzetbaarheid.

Papendal, May 2010

Nederlands Congres Volksgezondheid ‘In balans’. Oral: Op weg naar duurzame inzetbaarheid van werknemers; factoren die arbeidsparticipatie beïnvloeden..

Rotterdam, April 2010

Bedrijfsgeneeskundige dagen ‘De kracht van de bedrijfsarts’. Poster: Wat hebben oudere medewerkers nodig om (duurzaam) inzetbaar te blijven?

Papendal, May 2009

Lerend netwerk Work ability Index Noord‐oost Nederland. Oral: Lossen we de oorzaken op of zoeken we oplossingen?

Deventer, March 2009

Nederlands Congres Volksgezondheid ‘Vroeg erbij, beter meedoen’ . Poster: Bevorderen arbeidsparticipatie van de oudere werknemer met een chronische aandoening.

Groningen, April 2008

PUBLICATIONS

Koolhaas W, De Boer MR, Groothoff JW, Brouwer S, Van der Klink JJ.

Coping, job control and social support as adaptation determinants of work ability among ageing

workers with and without a chronic health condition. Submitted, September 2013.

Koolhaas W, Groothoff JW, De Boer MR, Van der Klink JJ, Brouwer S. Effectiveness of a problem‐

solving based intervention to improve sustainable employability of ageing workers. Submitted,

December 2013.

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206

Koolhaas W, Van der Klink JJ, De Boer MR, Groothoff JW, Brouwer S. Chronic health conditions and

work ability in the ageing workforce: the impact of work conditions and psychosocial factors. Int

Arch Occup Environ Health. 2013 May 16. [Epub ahead of print]

Koolhaas W, Van der Klink JJ, Vervoort JP, De Boer MR, Brouwer S, Groothoff JW. In‐depth study of

the workers' perspectives to enhance sustainable working life: comparison between workers with

and without a chronic health condition. J Occup Rehabil. 2013 Jun;23(2):170‐9. doi: 10.1007/s10926‐

013‐9449‐6.

De Vries H, Wessels M, Brouwer S, De Lange A, Koolhaas W, Van der Heijden B, Van der Mei S,

Bültmann U, Van der Klink J. Handreiking duurzame inzetbaarheid voor oudere werknemers, een

integrale benadering voor organisaties. Maart 2013, Universitair Medisch Centrum Groningen,

Rijksuniversiteit Groningen.

Brouwer S, De Lange A,Van der Mei S, Wessels M, Koolhaas W, Bültmann U, Van der Heijden B &

Van der Klink J. Duurzame inzetbaarheid van de oudere werknemer: stand van zaken. Overzicht van

determinanten, interventies en meetinstrumenten vanuit verschillende perspectieven. 2012, UMC

Groningen, Rijksuniversiteit Groningen. ISBN 978 94 6070 045 3

Koolhaas W, van der Klink JJ, Groothoff JW, Brouwer S. Toward a sustainable healthy working life:

associations between chronological age, functional age and work outcomes. Eur J Public Health.

2012 Jun;22(3):424‐9. Epub 2011 Mar 31 (Top publication award SHARE; top 25% artikel)

Koolhaas W, Brouwer S, Groothoff JW, van der Klink JJ. Enhancing a sustainable healthy working life:

design of a clustered randomized controlled trial. BMC Public Health, 2010; 10; 461

Jager PL, Jonkman S, Koolhaas W, Stiekema A, Wolffenbuttel BH, Slart RH. Combined vertebral

fracture assessment and bone mineral density measurement: a new standard in the diagnosis of

osteoporosis in academic populations. Osteoporos Int. 2011 Apr;22(4):1059‐68. Epub 2010 Jun 23.

Koolhaas W, Brouwer S, Groothoff JW, Sorgdrager B, van der Klink JJ. Bevorderen van de duurzame

inzetbaarheid van de oudere werknemer: langer doorwerken gaat niet vanzelf. Tijdschrift voor

Bedrijfs‐ en Verzekeringsgeneeskunde, 2009, 17;7:286‐291

Koolhaas W, Prak A, Stiekema HM, Kreeftenberg HG, Wolffenbuttel BH, Jager PL. Efficient and

improved diagnosis of osteoporosis by simultaneous bone density measurement and spinal

morphometry. Ned Tijdschr Geneeskd. 2008 Apr 19;152(16):938‐43. [Dutch]

Documents

University of Groningen Sustainable employability of ... · Sustainable employability of ageing workers The development of an intervention Proefschrift ter verkrijging van de graad