Assessing Health-related Quality of Life In

7/29/2019 Assessing Health-related Quality of Life In

1/9

Quality of Life Research, 7, pp. 399407

1998 Kluwer Academic Publishers Quality of Life Research.

Vol 7.

1998399

Assessing health-related quality of life inchronically ill children with the German KINDL:first psychometric and content analytical results

U. Ravens-Sieberer and M. Bullinger*

Department for Medical Psychology, University of Hamburg, Germany(U. Ravens-Sieberer, M. Bullinger)

Health-related quality of life is increasingly beingconsidered as a relevant end-point and outcomecriterion in evaluating the effects of medicaltreatment. While in adults quality of life instrumentshave been developed in terms of generic as well as

disease-specific measures, quality of life assessmentand children is a relatively new area. The currentpaper describes the application of a German genericquality of life instrument for children (the KINDL) in agroup of 45 chronically ill children suffering fromdiabetes or asthma in comparison to 45 age- andgender-matched healthy children. The results ofpsychometric testing in these populations showedthat the German KINDL is a reliable, valid andpractical instrument to assess the health-relatedquality of life of children which should be supple-mented by disease-specific modules and needs to befurther tested in clinical populations.Qual. Life Res. 7:399407 1998 Kluwer Academic Publishers

Key words: Children; quality of life; KINDL questionnaire;diabetes; asthma.

Introduction

The past years have seen an increase in theoretical andempirical papers on the topic of quality of life inmedicine. Current work, however, mostly concernsthe development of instruments and their applicationin studies with adults rather than children.1,2 Qualityof life in children is a relevant end-point for evaluating

the use of medical intervention in terms of prevention,in terms of treatment and in terms of rehabilitation forthis special patient group.3 These interventions notonly affect somatic parameters but also emotional and

social aspects of living for the patients concerned.Because of the far-reaching ramifications of interven-tions in their effects on patients it has been recognizedthat well-being and function are also important

treatment outcomes in children.Since the introduction of the quality of life conceptto medical research, over 20,000 publications have

appeared concerning the topic.3 Interestingly,however, only 13% of the publications identified arerelated to children (n = 3,050). Using a weighting forthe search terms quality of life and child resulted(e.g. for 1994 and 1995) in only 320 publications thatspecifically focus on quality of life in children. In the320 articles examined, the majority referred totheoretical or conceptional work (52%) and empiricalquality of life research in specific chronic conditions

(33%), while the testing of assessment instruments

(9%) or empirical quality of life research in general(6%) was less prominent. The paediatric populationsrepresented in these works mainly concern oncologyfollowed by transplantation medicine. The age rangeof the sample studies pertains mainly to children andadolescents of 1318 years while younger children inthe age range of 612 years have less frequently beenincluded in quality of life studies.

In spite of the different definitions of health-relatedquality of life in current literature,4,5 an internationalconsensus about the components of quality of lifewithin an operational definition of the term hasevolved. According to a recent definition, health-

related quality of life can be viewed as a psychologicalconstruct which describes the physical, mental, social,psychological and functional aspects of well-beingand function from the patient perspective.68 This

operational definition stresses the multidimension-ality of the quality of life concept as well as therelevance of patients self-report.

Although the four components of quality of life arenot exhaustive and do not constitute a taxonomy, theyheuristically denote the areas of importance to be

*To whom correspondence should be addressed at Abt. frMedizinische Psychologie, Universitt Hamburg,Kollaustrae 67/69-B, D 22529 Hamburg, Germany. Tel:+49-4717-6430; Fax: +49-4717-4940.


2/9

assessed when the quality of life of patients is under

study. The dimensionality of the quality of life concepthas been supported in studies with adults qualita-

tively and quantitatively as well as nationally andinternationally. It is questionable, however, whetherchildren choose comparable dimensions to describe

their health-related quality of life.9,10 The existing liter-ature regarding definitions of health from childrensviewpoints suggest that the construct of health is

viewed differently by children in comparison toadults.11 So far, the qualitative and quantitativeresearch into how children perceive dimensions of

well-being and function is insufficient. In addition, indevelopmental psychology and paediatrics, a childsperspective, as a reflection of his or her current state,

has not been sufficiently considered.1214

Recent reviews of the current literature on qualityof life and children show an increase in theoretical

articles referring to the importance of the problem buta lack of instruments to assess childrens quality oflife.3In terms of assessment, the most popularly used

methods are parent or staff assessment of child well-being, with over 90% of the studies showing that self-

report measures are lacking.Within the instruments, three approaches can be

distinguished. The first is a more clinical rating

approach, in which instruments are not developed intesting according to psychological quality criteria. Thesecond one is the utility-based approach, mostly

derived from health economic studies in adults, whichhas also been applied to children (for example, the

15D and 16D measures of the McMaster HealthEconomics group15) have been used in studies withadolescents). The third approach is the psychometricapproach. This approach has so far yielded the

relative majority of the measures available and can bedistinguished in terms of functional outcome

measures, such as the Paediatric Evaluation ofDisability Inventory (PEDI) of Haley et al.,16 moodmeasures represented, for example, by the Childrens

Depression Inventory17 and quality of life assessmentinstruments as such. Here generic and disease-specificmeasures can be distinguished. An example of the first

is the Child Health Survey by Landgraf et al.,12 while

an example of the second is the Childhood AsthmaQuestionnaire of Christie et al.18

Although various measures are currently beingdeveloped in the international arena, short, practi-cable, understandable instruments for assessing

health-related quality of life through childrens self-report are lacking.3 Owing to the recent tradition ofinstrument development in paediatric quality of life

research, the current article pertains to the devel-opment of a self-report generic quality of life

instrument for children from the psychometric

approach and describes the application of a newlydeveloped generic instrument for quality of life

assessment in children aged 816 years; the GermanKINDL questionnaire.19

The KINDL was derived from a conceptual model,

in which the four main components of quality of life,namely psychological well-being, social relationships,physical function and everyday life activities, were

included in interviews with children (several schoolclasses). The questionnaire consists of 40 items (Table1), reflecting each of the four above mentioned

subscales with nine or 11 items. The KINDL items arescored from 1 (never) to 5 (always) with reversalsaccording to the wording of the question and are

scored by the method of simple counted ratings of thescores per item, summarized and then transformed toa 0100 scale. The items were constructed and pre-

tested in two pilot studies involving 28 children each.The KINDL was included in an environmental,

psychological, 3 year, observational study of 345

healthy children. The first part of this study was usedto analyse the psychometric properties of the

instrument and the second part served as thenormative data set. The results indicated sufficientreliability (Cronbachs > 0.70) and validity (correla-

tions with instruments measuring similar concepts,r = 0.70). Sensitivity to change in the childrens livingconditions could also be demonstrated. Although the

four-dimensional structure of quality of life wassupported by factor analysis, the KINDL factors were

not independent of each other and some items alsocorrelated with the other scales. With the question-naire, however, it was possible to differentiate

between children with regard to health state, actual

life events and concomitant developmental condi-tions, while no gender effects were found. Over time,

the testretest correlations of the subscales wererelatively high (r = 0.80) in children with no change inenvironmental conditions, while change (e.g. the

onset of aircraft noise exposure) did significantlyimpair the quality of life of children.

The KINDL has also been used in a longitudinal

German public health study involving over 500

children and is currently being used in several clinicalstudies involving chronically ill children. While

existing data about healthy children do support thepsychometric quality of the generic KINDL question-naire, a comparable analysis of the KINDL in popula-

tions with chronically ill children has not yet beenconducted.

The goal of the current study was an evaluation of

the KINDL in chronically ill children with thefollowing research questions.

U. Ravens-Sieberer and M. Bullinger

400Quality of Life Research

.Vol 7

.1998


3/9

Table 1. The KINDL dimensions and items

Functional capacity

in everyday life Psychological well-being Physical state Social relationships

During the last week... During the last week... During the last week... During the last week...

It was easy for me to I felt grumpy and moody I felt queasy or nauseous My parents were nice to me

do my homework

I enjoyed classes at I felt stressed out I was able to sleep well I played with my fr iends in

school the afternoon

I made a lot of mistakes I was worn out and tired I horsed around a lot I got along well with my

on my homework parents

I had difficulty I did not feel like doing I felt ill I felt comfortable at home

concentrating anything with my family

I was forgetful and I had trouble at home I had headaches or I laughed a lot and had fun

absent-minded stomach aches

I had problems with I had a lot of good ideas I was in top physical I enjoyed being with my

my teachers condition friends

I was nervous and Everything got too much I felt l ively and alert Everyone nagged at me

fidgety for me to handle

I was proud of my I was cheerful and in a I ached all over I was praised and

achievements good mood commended

Everything I started I felt frightened or I had a lot of strength I was a success among my

worked out insecure and endurance friends

Everything got on my I felt along and deserted

nerves

I was satisfied with myself I was upset because

some things went wrong

(1) Is the KINDL a reliable, valid and practicable

instrument to assess health-related quality of life

in chronically ill children?

(2) Is there a relationship between psychosocial

factors and health-related quality of life in chroni-

cally ill children?

(3) How do the KINDL results compare to qualita-

tively analysed answers to open questions

regarding quality of life?

Methods

A total of 145 patients from a German childrens

hospital, aged 1016 years, were included in a cross-

sectional study with repeated measurement. The

inclusion criterion was a diagnosis of either juvenile

diabetes or bronchial asthma. These conditions were

chosen because they reflect the common problems of

chronic conditions in childhood and both imply

psychological adaptation in terms of control, coping,

compliance and stigma. In terms of the physical

impact and transparency of the conditions, diabetesand asthma are diverse.

The healthy control children were identified fromthe above-mentioned public health study on 530

children using the method of matching so that eachchronically ill child was paired with a child from the

healthy reference group comparable in terms of age,gender and schooling level.

An inventory was developed for the study, inwhich the KINDL, as well as other scales to assess

quality of life, were included, i.e. three subscales from

the Short Form-36 Health Survey (SF-36),20 physicalhealth, mental health and vitality, as well as a Germanquestionnaire for life satisfaction (FLZ).21 Further

information on the potential psychosocial determi-

nants of quality of life related to physical complaints,difficulty in sleeping, health locus of control, health

behaviour, stress level, social support, concepts ofdisease and health as well as sociodemograhic data

was collected, as well as questions relating to thepracticability of the KINDL. The items for the

Quality of life assessment in children with the KINDL

Quality of Life Research.

Vol 7.

1998401


4/9

assessment of these psychosocial determinants were

derived from existing standard German scalesassessing these concepts. In addition to child self-

report, mothers information about their own qualityof life as well as the mothers perceptions of thechildrens self-reported well-being were included.

Here, the mothers ratings were not used as proxyindicators for childrens quality of life but rather as ameasure of empathy: to what extent can mothers

reproduce childrens self-reported assessments whenasked how do you think your child feels and hasresponded to the questionnaire questions?.

The questionnaires for the children as well as thosefor one parent were mailed to 145 patients currentlyunder treatment at the childrens hospital and

included a pre-addressed return envelope as well asan informed consent sheet. In addition to thesestandard scales, open questions relating to percep-

tions and descriptions of relevant quality of lifedimensions from the childrens view were included.The data collection took place during a defined time

period of 4 weeks, in which patients currently beingtreated at the childrens hospital as well as one parent

were contacted with regard to their willingness toparticipate in the study.

The psychometric evaluation of the questionnaire

included testing for its reliability (internal consistencyas well as testretest reliability within a 1 weekinterval) and validity (convergent and construct

validity). Convergent validation was performed bycorrelating the subscales of the KINDL with the

subscales of the FLZ and Short Form-36 HealthSurvey. The discriminant validity was assessed via theknown groups approach, i.e. testing of the differences

between patient populations according to criteria

within an assumed difference in quality of life (i.e.healthy versus ill and type and severity of chronic

disease). Known group comparisons have beenwidely used, particularly in health outcomes research2

and are acceptable means of assessing validity. Here

the known group confirmation refers to the differ-ences between healthy and ill children, a comparison

based upon the impact of a chronic condition on well-

being.

The sociodemographic data as well as psychosocialdeterminants were related to quality of life with corre-

lational analysis as well as difference testing (t-tests).For the age-related analysis an age split after 13 yearswas used; in developmental psychology, an age split

above the age of 13 years is common because it reflectsthe transition from childhood into early adolescenceor puberty. It can be assumed that older children may

differ from younger ones in terms of the specific age-related demands of the disease which is why this

analysis was included.

The responses to the open questions were content

analysed by the development of categories from twoindependent raters, followed by using a statistical

procedure for qualitative content analysis (the

program: AQUAD). In addition, the acceptance and

practicability of the KINDL was assessed usingchildrens ratings of its understandibility, personal

relevance and time needed for filling in the items.

Results

Sociodemographic characteristics

Of the 145 families with chronically ill children

contacted, 45 children and 45 mothers were interestedin participating in the study (response rate 31%). The

45 children (23 girls and 22 boys) were 1016 years old(mean = 13.2 years and SD = 2.7 years) and 56% were13 years or younger.

Approximately one-third of the children were at

higher elementary level schooling, another third wereat lower secondary level and the last third were at

higher secondary level. Of the 45 children, two-thirds

suffered from diabetes and one-third from asthma.

Psychometric results

The questionnaire was filled in by all of the children of

the participating families with good quality responses(missing data 0.1%). Systematic response tendencies

such as the identity of answers for different items



.Vol 7

.1998

Table 2. Sociodemographic characteristics

Chronically ill children n = 45

Gender

Girls 51%

Boys 49%

Age

Mean ( SD) (years) 13.2 ( 2.7)Range (years) 1016

1013 years 56%

1416 years 44%

School

Elementary 28%

Lower secondary 38%

Higher secondary 34%

Control group: 45 healthy children as matched pairs.


5/9

were not found. In addition, the positively andnegatively pooled responses were filled in consis-

tently. The children needed 12 min on average to fill in

the KINDL and a mean of 34 min to fill in the totalquestionnaire packet. With regard to the KINDL, a

frequency analysis showed good use of the answerscales, in that the ceiling and floor effects on a subscale

level were under 2.5%. Confirmatory testing of the

internal consistency showed that all of the subscalesreached an coefficient of over 0.75; the Cronbachs

for the total scale was 0.95. In general, the reliabilitycoefficients for the chronically ill children were

slightly higher than for the reference group of healthy

children (Table 3). With regard to the validity, theconvergent validation between the KINDL subscales

and SF-36 or FLZ subscales showed significant corre-

lations of a magnitude ofr = 0.70 for the mental healthand vitality scales as well as for physical functioning.

The general health scale had lower correlation coeffi-cients (r = 0.380.52 (Table 4). The intercorrelations of

the KINDL scales within the group of chronically illchildren were high (r = 0.540.95), as were the correla-

tions in the healthy sample for the subscales, with the

total scale ranged around r = 0.75 (Table 5). In terms ofpracticability, 95.5% of the chronically ill children

found the questions easily understandable; 60% of the

children judged the questions to be very relevant,while another 20% judged them to be relevant to their

current situation.

Determinants of quality of life

With regard to the sociodemograhic data, no signif-

icant differences between girls and boys in terms of

quality of life evaluations were found. Only with

regard to the psychosocial variable sleeping diffi-

culties did chronically ill girls indicate significantly

more difficulties than boys (p = 0.016). The mediansplit of the group below and above 13 years showed

that age differences exist in the KINDL in that younger

children indicated a significantly higher quality of life

than older children (p = 0.001). These children also

reported a healthier lifestyle (less unhealthy food,

more sports activity and less smoking (p = 0.005). The

type of schooling did not affect quality of life and the

two disease groups (diabetes and asthma) only

differed with regard to their health behaviour but notto their quality of life. In general, children with

diabetes showed significantly more risk prone health

behaviour than did the children with asthma(p = 0.025).

Potential psychosocial influence factors on quality

of life were also tested and included internal versus

external locus of control, stress level and social

support. There was a significant high correlation

between health-related quality of life and social

support (r = 0.50 and above) and an even higher corre-

lation between the quality of life summary scale and

stress level (r = 0.70). No significant differences



Vol 7.

1998403

Table 3. Structure of the scales and reliability

Chronically ill children Healthychildren

Internal Internal

KINDL Number Floor Ceiling consistency Floor Ceiling consistency

scales of items Mean SD (%) (%) () Mean SD (%) (%) (%)

Mental 11 3.6 0.76 0.0 2.2 0.89 4.0 0.54 0.0 2.0 0.76

Physical 9 4.1 0.57 0.0 0.0 0.76 4.0 0.55 0.0 1.9 0.79

Everyday life 11 3.7 0.71 0.0 0.0 0.89 3.9 0.51 0.0 2.0 0.89

Social life 9 3.9 0.65 0.0 2.2 0.84 4.0 0.46 0.0 2.1 0.74

Total 40 3.7 0.70 0.0 0.0 0.95 4.0 0.43 0.0 2.3 0.90

Table 4. Correlation between the KINDL, SF-36 and FLZ

Scales General health Mental health Vitality FLZ

Mental 0.43 (p = 0.004) 0.86 (p = 0.000) 0.72 (p = 0.000) 0.76 (p = 0.000)

Physical 0.52 (p = 0.000) 0.59 (p = 0.000) 0.67 (p = 0.000) 0.58 (p = 0.000)

Everyday life 0.38 (p = 0.014) 0.79 (p = 0.000) 0.75 (p = 0.000) 0.64 (p = 0.000)

Social life ns 0.62 (p = 0.000) 0.53 (p = 0.000) 0.78 (p = 0.000)

Total KINDL 0.38 (p = 0.013) 0.77 (p = 0.000) 0.74 (p = 0.000) 0.65 (p = 0.000)


6/9

between the healthy and ill children were found in the

KINDL subscales or in the FLZ and SF-36 subscales.

However, the healthy children reported slightly

higher quality of life scores which almost reached

significance levels for the psychological well-being

subscale and total score (p = 0.059 and p = 0.057,

respectively) (Figure 1).

Content analytical results

The concepts of health and illness of chronically ill

children were identified via a qualitative content

analysis of the answers to the open questions with a

subsequent frequency analysis of the categorized

answers. The questions related to the concepts of

disease included negative associations concerning the

disease in terms of the actual person, self and family

as well as difficulties in coping with the disease. The

negative associations related to the disease showed adistribution of the responses into three categories.

Over one-third of the children reported the occurrence

of massive physical symptoms such as pain and

breathing difficulty as concomitants of the disease.

Disease as an experience in everyday life which influ-

ences daily activities and which prescribes or forbids

specific activities (for example, regular blood sugar

controls, taking medications or adhering to a diet) wasreported by nearly half of the children. Most of thechildren indicated the negative position in which thedisease places them vis--vis family, friends or societyas a whole, referring to stigmatization, poor self-image or overprotection. Generally, the quantitative

questions showed that 51% of the children found thedisease rather to extremely disturbing and 31%

indicated that the family was substantially affected bythe disease. Only approximately 20% of the childrenindicated that they did not find themselves experi-encing problems due to the disease.

In a more specific question, information about thefamily burden of the chronic condition was solicited.Most frequently noted was the disease as a majorlimiting factor in family life: overprotection by parentsor a massive problem with self-worth, e.g. patients

viewing themselves as less valuable than theirsiblings. In addition, financial problems (the costs of

treatment and medication) as well as physicalproblems (being not as healthy as others) were thepredominant negative associations of the childrenwith regard to the family.

The second question concerning difficulties indealing and coping with the disease included four

categories. The first category concerns the stress of theobservance of rules and the regularity of the livingconditions caused by the disease (regular meals androutine medical examinations) was viewed as onemain difficulty by more than 60% of the children.Physical problems such as low blood sugar andasthma attacks was noted by 20% of the children and

10% complained of social isolation due to the disease;here the problems of being accepted as a person inspite of the disease and finding friends were specifi-cally noted. Only a small percentage of the childrenindicated no problems in coping with the disease(6%). A last open question addressed the childrenshopes and wishes for the future. Almost half of thechildren (48%) basically wished restored health or areduction of the symptoms. Many children reported

the wish to be free of the disease-specific limitations,



.Vol 7

.1998

Table 5. Intercorrelation between the subscales

KINDL scales Mental Physical Everyday life Social life Total

Mental 0.63 0.78 0.75 0.81

Physical 0.63 0.54 0.59 0.58

Everyday life 0.78 0.54 0.60 0.94

Social life 0.75 0.59 0.60 0.62

Total 0.81 0.58 0.94 0.62

Figure 1. Differences in quality of life (KINDL)


7/9

that is they viewed the freedom from diet and injec-tions as a prerequisite to leading a normal life, such aseating anything (especially sweets), being physicallyactive and having more friends which was currentlyprecluded the disease. Wishing improvement wasvoiced by 9% with regard to easier methods of

assessing blood sugar levels or injecting insulin and3% of the children wished new organs such as a newpancreas or lungs. In general, the results of the contentanalysis showed the amount of difficulty andproblems experienced by the children in relation tothe disease and the wish to be free of the disease-related limitations.

Discussion

Quality of life as a concept pertains to well-being and

function as perceived by adults and children. Sincequality of life assessment in the adult arena can onlybe cautiously transferred to childrens quality of lifeexperiences, paediatric research needs to address thepsychosocial effects of disease and treatment specifi-cally so that better care can be delivered to chronicallyill children.16 One prerequisite for such an evaluationis the development and testing of instruments toassess childrens health-related quality of life, such asthe KINDL questionnaire.

The basis of the development of the KINDL is amixture of a top-down and bottom-up approach. Interms of the top-down approach, quality of life dimen-

sions relevant for adults are tested with regard to thequestion of whether they are also reflected inchildrens experiences. At the same time, with theopen question the bottom-up approach is followed bytrying to assemble from the childrens own experi-ences and viewpoints relevant dimensions of qualityof life.

The current study shows that the KINDL isaccepted by chronically ill children suffering fromdiabetes or asthma and is a practicable researchinstrument. Psychometrically, the questionnaire fulfilsthe basic psychometric criteria in terms of the varianceof items, low ceiling and floor effects of the scales,

high internal consistencies and a good convergentvalidity. However, the scale intercorrelations showthat the KINDL subscales are strongly correlated sothat differentiating between subscales might beproblematic. The components of quality of life asassessed by the KINDL seem to be strongly dependenton each other in the experience of the children.

As an empirical finding, the correlations betweenthe quality of life subscales have often been reportedto be high. In the case of the KINDL, the structural

independence of the components does not pose a

serious threat to the instrument. High correlations,however, reduce the possibility of arriving at differ-

ential patterns of quality of life as associated withvarious clinical conditions. A solution to the problemis to use a higher order factor analysis, which can,

however, only be applied in a larger sample of chron-ically ill children. Furthermore, it has to be consideredthat the strong relationship between the dimensions

correctly reflects the fact that, in childrens minds, thequality of life dimensions are not as differentiated ascould be expected.

Although the correlation of the KINDL subscaleswith quality of life instruments such as the SF-36 andFLZ are significant and high and, thus, demonstrate

high convergent validity, they only explain between15 and 50% of the common variance. This suggeststhat unidimensional assessments, e.g. of life satis-

faction, do not fully reflect childrens experiences andthat instruments conceived for health-related quality

of life assessment in adults might not be appropriatefor children. The sociodemographic factors were onlyweakly related to the quality of life of chronically ill

children which has also been reported in recent liter-ature.22 However, an age effect was present, indicatingthat younger children rate their quality of life higher

as compared to older children, which from a develop-mental perspective can be attributed to a higher stresslevel with the beginning of puberty.13

In addition, the quality of life scores of asthma anddiabetes patients do not differ significantly from each

other which suggests that either the disease-relatedstressors are comparable for both groups or that thespecific strains of each disease were not sufficientlygrasped by the generic instruments. The reasons for

including children with diabetes and asthma pertainto the fact that both chronic conditions have implica-

tions for disease management in terms of compliance,but, however, they have differences in terms of theaccompanying stigmas associated with these diseases.

It was hypothesized that children with asthma wouldin particular show a more pronounced impairment inquality of life as relates to the social dimension, while

in the physical and psychological dimension these

differences were not expected. Differences betweenboth diabetic and asthmatic children and healthy

children were expected in terms of an assumed higherrating of the quality of life dimensions in healthychildren due to the absence of a chronic condition.

With regard to differentiating chronically ill fromhealthy children, the KINDL, FLZ and SF-36 showedtrends which failed to reach significance . In the SF-36

subscale general health a significant group differenceappeared, indicating that chronically ill children feel



Vol 7.

1998405


8/9

impaired here. In the KINDL, the psychological well-

being subscale and total score slightly exceeded the

significance level, indicating a similar impairment.

Since the SF-36 general health score correlates only

weakly with the KINDL subscales, the experience of

the children captured by the SF-36 scale might reflect

other health-relevant dimensions.The lack of differences in quality of life between

healthy and ill children can be explained as follows.

(1) The sample size was insufficient to yield signif-

icant results, which implies that in a larger

population the differences in the KINDL psycho-

logical well-being subscale and in the total score

would have been significant. The current study

was based on questionnaires being mailed to

former out-patients of a childrens hospital, who

were not under close surveillance or contact with

the clinics. Given this, the 30% response rate is not

ideal, but to be expected in a situation whereparents as well as children have frequently

undergone studies and investigations. Given the

limited sample size, the fact that the differences

between chronically ill and healthy children just

failed to reach significance for two scales (the

KINDL psychological well-being subscale and the

total score) is encouraging.

(2) There is a selection bias in that only families who

did not feel substantially limited in their health-

related quality of life by the disease participated

and filled in the questionnaire and are thus

comparable to healthy families. However, in theirclinical data, the responding children did not

differ from the non-respondents.

(3) Healthy and ill children in fact do not differ with

regard to their health-related quality of life, a

result which has also been reported in adults

studies.23 Support for this hypothesis is the

relationship between psychosocial factors and

quality of life which is similar for chronically ill

and for healthy children. However, the answers to

the open questions stress the importance of the

disease for the chronically ill childrens quality of

life and suggest that only a small impact of

disease on the childrens quality of life is unlikely.(4) Chronically ill children might report a particularly

high quality of life because of successful coping

processes. The role of denial, for example, has

been reported with regard to the self-concept of

children with diabetes.11

(5) The KINDL is not able to differentiate between

healthy and ill children because it is too generic in

nature and does not contain questions of specific

relevance to chronically ill children suffering from

chronic conditions. This suggests that a generic

quality of life questionnaire should be supple-

mented by a disease-specific supplement whichtakes into account the specific situation of the

paediatric clinical population.

In sum, the results of evaluating the KINDL inchronically ill children in comparison to healthy

children showed that an instrument for health-related

quality of life assessment in children is availablewhich is economic and promising but needs further

work in terms of the independence of its subscales, itsdiscriminant power and a modular supplement

grasping the specific problems and limitations inquality of life due to chronic conditions.

In addition, the role of external assessment (i.e.

family and staff) of childrens quality of life needs tobe explored further. In the present study, the mothers

data were collected, which reflected that mothers

perceptions of childrens quality of life is not aconvergent validation of childrens views, but theirown and independent viewpoints. Though not

reported, the results indicate that it is not a contra-diction to ask both a mother and child about the

childs quality of life, if it is clear that the mothers

view cannot be taken as substitute for the childsexperience.

The KINDL is a German generic psychometricallybased, self-report measure for children, which has

already gained wide-spread use in Germany as well as

elsewhere (English translations are available andItalian, Dutch and French translations are under way).

A longitudinal study using the KINDL in 130 childrensuffering from asthma is currently being conducted.

Further studies with bigger sample sizes are needed toexamine the potential use of the KINDL in epidemio-

logical and clinical studies and in routine clinical care.

References

1. Walker SR, Rosser RM. Quality of Life Assessment andApplication. Lancaster: MTP Press, 1991.

2. Stewart AL, Ware J. Measuring Function and Well-being.Durham, NC: Duke University Press, 1992.

3. Bullinger M, Ravens-Sieberer U. Health related quality oflife assessment in children. Eur Rev Appl Psy 1995:245254.

4. Calman KC. Definitions and dimensions of quality of life.In: Aaronson N, Beckman J, Bernheim J, Zittoun R, eds.The Quality of Life of Cancer Patients. New York: RavenPress, 1987: 8197.

5. Spilker B. Quality of Life Assessment in Clinical Trials. NewYork: Raven Press.

6. Bullinger M. Quality of life definition, conceptual-ization and implications a methodologists view. TheorSurg 1991: 143149.



.Vol 7

.1998


9/9

7. Furberg CD. Assessment of quality of life. In: FriedmanL, Furberg C, Demets D, eds. Fundamentals of ClinicalTrials. Littletown: PSG Publishing, 1985.

8. Levine S, Croog SH. What constitutes quality of life? Aconceptualization of the dimension of life quality inhealthy populations and patients with cardiovasculardisease. In: Wenger N, Mattson M, Furberg C, Ellison J,

eds. Assessment of Quality of Life in Clinical Trials ofCardiovascular Therapies. New York: Le Jacq, 1984: 4466.

9. WHOQOLGroup. The development of the WHO qualityof life assessment instruments (WHOQOL). In: Orley I,Kaykyen W, eds. Quality of Life Assessment, InternationalPerspectives. Berlin: Springer, 1994: 3340.

10. Barr RD, Pai MKR, Weitzman S. A multi-attributeapproach to health status measurement and clinicalmanagement illustrated by an application to braintumors in childhood.Int Oncol 1994: 639648.

11. Seiffge-Krenke I. Krankheitsverarbeitung bei Kindern undJugendlichen. Jahrbuch der Medizinischen Psychologie.Heidelberg: Springer, 1990.

12. Landgraf I, Abetz L, Ware I. Child Health Questionnaire(CHQ): A Users Manual. Boston: The Health Institute

Press, 1997.13. Oerter R, Montada L. Entwicklungspsychologie . Mnchen:

Lang P, 1987.14. Wahn U, Szepauskk R, Bullinger M. Chronische Kranke

Kinder. Stuttgart: Rupp Verlag.15. Feeny D, Furlong W, Barr RD, Torrance GW, Rosenbaum

P, Weitzmann S. A comprehensive multi-attribute system

for classifying the health status of survivors of childhoodcancer.J Clin Oncol 1992: 10(6): 923928.

16. Haley SM, Coster W, Ludlow I et al. Pediatric Evaluation ofDisability Inventory (PEDI). Development, Standardizationand Administration Manual. Boston: New EnglandMedical Journal, 1992.

17. Kovacs M. The Childrens Depression Inventory (CDI).

Psychopharmacol Bull 1985: 21: 995999.18. Christie MJ, French D, Sowden A, West A. Development

of child-centered disease-specific questionnaires forliving with asthma. Psychom Med 1993: 55: 541548.

19. Bullinger M. KINDL a questionnaire for health-relatedquality of life assessment in children. Zeitschrift frGesundheitspsychologie 1994: 1: 6477.

20. Ware I, Sherbourne C. The MOS 36-item short formhealth survey SF-36: international conceptual frameworkand item selection.Med Care 1992: 30: 473481.

21. Henrich G, Herschbach P. Fragen zur Lebenszufried-enheit (FLZ), 1992. In: Schwarz R, ed. Lebensqualitt in derOnkologie II. Mnchen Zuickschwerdt, 1995: 7793.

22. Bullinger M, Ravens-Sieberr U. Stand der forschung zur

gesundheitsbezogenen lebensqualitt von kinderneineliteraturanalyse. Prv Rehab 1995: 106121.23. Petermann F. Lebensqualitt und Chronische Krankheit.

Mnchen: Dustri, 1993.

(Received 26 February 1997;accepted 9 September 1997)



Vol 7.

1998407

Documents

Assessing Health-related Quality of Life In