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A Systematic Review of Workplace Ergonomic Interventionswith Economic Analyses
Emile Tompa • Roman Dolinschi •
Claire de Oliveira • Benjamin C. Amick III •
Emma Irvin
Published online: 5 November 2009
Springer Science+Business Media, LLC 2009
Abstract Introduction This article reports on a systematic
review of workplace ergonomic interventions with eco-nomic evaluations. The review sought to answer the ques-
tion: ‘‘what is the credible evidence that incremental
investment in ergonomic interventions is worth undertak-
ing?’’ Past efforts to synthesize evidence from this literature
have focused on effectiveness, whereas this study synthe-
sizes evidence on the cost-effectiveness/financial merits of
such interventions. Methods Through a structured journal
database search, 35 intervention studies were identified in
nine industrial sectors. A qualitative synthesis approach,
known as best evidence synthesis, was used rather than a
quantitative approach because of the diversity of study
designs and statistical analyses found across studies. Evi-
dence on the financial merits of interventions was synthe-
sized by industrial sector. Results In the manufacturing and
warehousing sector strong evidence was found in support of
the financial merits of ergonomic interventions from a firm
perspective. In the administrative support and health care
sectors moderate evidence was found, in the transportation
sector limited evidence, and in remaining sectors insuffi-
cient evidence. Conclusions Most intervention studiesfocus on effectiveness. Few consider their financial merits.
Amongst the few that do, several had exemplary economic
analyses, although more than half of the studies had low
quality economic analyses. This may be due to the low
priority given to economic analysis in this literature. Often
only a small part of the overall evaluation of many studies
focused on evaluating their cost-effectiveness.
Keywords Economic evaluation Ergonomics
Systematic review
Introduction
Workplace ergonomic programs are implemented to help
ensure that work systems (equipment, tools, work stations,
work and workplace organization and policies/procedures)
enhance employee health and safety and optimize business
performance (i.e. efficiency, productivity, quality and
profitability). In the last few years, there has been increasing
recognition of the importance of ergonomics in workplace
settings. The scientific evidence on the effectiveness of
ergonomic programs, policies and practices for reducing
injuries is less robust than one might expect despite the
increased use of ergonomic standards and guidelines [1].
Several systematic reviews have investigated the effec-
tiveness of ergonomic interventions. Among them, Rivilis
et al. undertook a systematic review of the effectiveness
of participatory ergonomic interventions [2]. The review
found partial to moderate evidence that participatory ergo-
nomic interventions can reduce musculoskeletal (MSK)
symptoms, workers’ compensation claims and sickness
absence. Brewer et al. conducted a systematic review of
E. Tompa (&) R. Dolinschi C. de Oliveira
B. C. Amick III E. Irvin
Institute for Work & Health, 481 University Avenue, Suite 800,
Toronto, ON M5G 2E9, Canada
e-mail: [email protected]
E. Tompa
Department of Economics, McMaster University,
Hamilton, ON, Canada
E. Tompa
Dalla Lana School of Public Health, University of Toronto,
Toronto, ON, Canada
B. C. Amick III
School of Public Health, University of Texas
Health Science Center, Houston, TX, USA
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J Occup Rehabil (2010) 20:220–234
DOI 10.1007/s10926-009-9210-3
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in a peer-reviewed journal were considered. Third, studies
were excluded based on several criteria concerning context
and subject matter: (1) if the intervention was undertaken in
a developing country (based on the notion that the OHS
context in developing countries is very different than that in
developed countries); (2) if the industry/context was army-
related or on a military base; and (3) if the intervention was
focused exclusively on non-health consequences such ascost reduction and/or productivity/quality improvement
(these were included only if there was a primary or sec-
ondary prevention outcome). For example, an engineering
study that focused on redesigning equipment and work flows
to increase productivity, without considering or measuring
health consequences would not be included. In contrast, a
study that focused on reducing insurance costs, would be
included if it gave consideration to the health outcomes
underlying insurance claims and costs.
Quality Assessment
All studies that met the subject matter and other inclusion
criteria were retained for quality assessment and data
extraction. The quality assessment tool we developed was
based on a recently published environmental scan of OHS
intervention studies with economic analyses that reviewed
methodological issues and identified guidelines for good
practice [8]. The guidelines consist of 10 issues to consider
in an economic evaluation, clustered under three broad
categories: (1) study design and related factors, (2) mea-
surement and analytic factors, and (3) computational and
reporting factors. These guidelines have been expanded
upon and discussed at length in an economic evaluation
methods text for researchers [9]. We refer readers to these
sources for details.
The questions in the quality assessment tool were divi-
ded into four sections: (1) overarching issues that frame the
purpose of the study and the nature of the intervention; (2)
study design and issues related to evaluating the interven-
tion’s effectiveness; (3) measurement and analytic issues
related to the economic analysis; and (4) issues related tothe discussion and interpretation of results. The tool’s
primary focus was to assess the quality of evidence related
to the economic analysis, though consideration was given
to the effectiveness analysis.
The quality assessment tool included 14 questions
(Table 1). Each item was ranked on a five-point Likert
scale, where one corresponded to the lowest score and five
to the highest. Use of a Likert scale to assess the quality of
a study on a particular dimension is a common technique in
best-evidence synthesis. In some cases where a question
was not applicable to a particular study the question was
labeled ‘NA’ and was not counted in the quality assessmentscoring for that study.
Two reviewers with expertise in the economic evalua-
tion of OHS interventions assessed the quality of each
study. The reviewers met on a regular basis to discuss their
assessment of each study. The intent of these meetings was
not to reach consensus, but rather to ensure that the quality
assessment of each study was based on a sound consider-
ation of all relevant aspects of the study.
The average score across the 14 items in the tool con-
stituted the overall study score given by a reviewer. The
average of the overall scores between the two reviewers
constituted the final study score. A study with a final score
Table 1 Quality assessment
tool Overarching questions that frame the purpose of the study and the nature of the intervention
(1) Was the conceptual basis of, and/or the need for the intervention explained and sound?
(2) Was the intervention clearly described?
(3) Were the study population and context clearly described?
Study design and issues related to evaluation of the intervention’s effectiveness
(4) Rank the means by which selection and confounding are controlled for through study design?
(5) Were appropriate statistical analyses conducted?
(6) Are exposure, involvement, and intensity of involvement in the intervention appropriate?
(7) Are the outcomes included in the analysis appropriate?Measurement and analytic issues related to the economic evaluation
(8) Were all relevant comparators explicitly considered?
(9) Was the study perspective explicitly stated and appropriate?
(10) Were all important costs and consequences considered in the analysis, given the perspective?
(11) Are the measures of costs and consequences appropriate?
(12) Was there appropriate adjustment for inflation and time preference?
(13) Was there appropriate use of assumptions and treatment of uncertainty?
Discussion and interpretation of results
(14) Did the presentation and discussion of study results include all issues of concern?
222 J Occup Rehabil (2010) 20:220–234
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between 1 and 2.4 was considered to provide low quality
evidence related to the economic analysis. A final score
between 2.5 and 3.4 represented medium quality, and a
score between 3.5 and 5 indicated high quality. Only
studies receiving a score in the medium and high quality
range were retained for evidence synthesis.
Data Extraction
Data extraction focused on four areas of the study: (1)
contextual factors such as jurisdiction, industry and occu-
pational group targeted; (2) details of the intervention; (3)
characteristics of the epidemiologic design and related
statistical analyses; and (4) characteristics of the economic
evaluation. In total there were more than 40 items extracted
from each study [6]. Although all studies meeting subject
matter inclusion criteria underwent data extraction, only
medium and high quality studies were included in evidence
synthesis.
Evidence Synthesis
The primary stratification for evidence synthesis was by
industrial sector. Evidence was also synthesized across all
studies regardless of sector, and also for the subset of
studies that were about participatory ergonomic interven-
tions. Slavin’s best evidence synthesis approach was used
for this purpose [4, 5]. As noted, it is a qualitative approach
that assesses the level of evidence on a particular rela-
tionship based on the quality, quantity and consistency of
findings in the relevant studies.
The level of evidence was ranked on a five-category scale
consisting of strong evidence, moderate evidence, limited
evidence, mixed evidence and insufficient evidence.
Evidence for a particular stratum of studies was first tested
against the criteria for the strong evidence, and if it was not
met, the criteria for moderate evidence were considered. If
these criteria were not met, the criteria for limited evidence
were considered. If the evidence did not meet any of the
criteria for the three levels, then it fit into one of the two
categories, mixed evidence or insufficient/no evidence. The
evidence ranking algorithm can be found in Table 2.
Stakeholder Involvement
An advisory committee consisting of representatives from
the policy arena (from the workers’ compensation authority
and from the Ministry of Labour in Ontario, Canada), rep-
resentatives from the provincial health and safety associa-
tions in Ontario, a private sector business representative, and
a senior academic researcher in the ergonomics field was
formed to guide the design and execution of this systematic
review. The group met at three points during the systematic
review process. The committee was consulted at the initialstages of developing the project, mid-way when study
identification stage had been completed and near the end of
the project when the final report was being developed. The
committee was consulted to get feedback on aspects of the
review such as subject matter framing, review scope, search
strategy, synthesis criteria and presentation of findings.
Results
Literature Searches
The MEDLINE search resulted in 6,381 hits, EMBASE in
6,696 hits, BIOSIS in 2,568 hits, Business Source Premier
Table 2 Criteria for levels of evidence
Level of evidence Minimum criteria
Strong Three high quality studies agree on the same findings
(If there are more than three studies, then at least 75 per cent of medium and high quality studies agree.)
Moderate Two high quality studies agree
or
Two medium quality studies and one high quality study agree
(If there are more than three studies, then at least 67 per cent of the medium and high quality studies agree.)
Limited There is one high quality study
or
Two medium quality studies that agree
or
One high quality study and one medium quality study that agree
(If there are more than two studies, then at least 50 per cent of the medium and high quality studies agree.)
Mixed None of the above criteria are met and findings from medium and high quality studies are contradictory
Insufficient There are no high quality studies, only one medium quality study and/or any number of low quality studies
J Occup Rehabil (2010) 20:220–234 223
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T a b l e 4
D e t a i l s o f h i g h a n d m e d i u m q u a l i t y s t u d i e s
S t u d y
D e R a n g o e t a l . [ 1 2 ]
L a h i r i e t a l . [ 1 3 ]
R e m p e l e t
a l . [ 1 0 ]
C o l l i n s e t a l . [ 1 5 ]
S e c t o r
A d m i n i s t r a t i v e a n d S u p p o r t
A d m i n i s t r a t i v e a
n d S u p p o r t
A d m i n i s t r a t i v e a n d S u p p o r t
H e a l t h C a r e
C o u n t r y
U n i t e d S t a t e s
U n i t e d S t a t e s
U n i t e d S t a
t e s
U n i t e d S t a t e s
I n t e r v e n t i o n
d e t a i l s
H i g h l y a d j u s t a b l e c h a i r a n d a o n e - t i m e
o f fi c e e r g o n o m i c s t r a i n i n g w o r k s h o p
w i t h a s e r i e s o f
e d u c a t i o n a l f o l l o w - u p s
c o n d u c t e d c o n c
u r r e n t l y w i t h t h e c h a i r
d i s t r i b u t i o n
L u m b a r p a d s a n d b a c k r e s t s w e r e m a d e
a v a i l a b l e t o e m
p l o y e e s t o r e d u c e b a c k
d i s c o m f o r t . B a c k s c h o o l w o r k s h o p s w e r e a l s o
c o n d u c t e d
F o u r w o r k p l a c e i n t e r v e n t i o n s c o m p a r e d :
I n t e r v e n t i o
n A : e r g o n o m i c s t r a i n i n g
I n t e r v e n t i o
n B : t r a c k b a l l a n d e r g o n o m i c
t r a i n i n g
I n t e r v e n t i o
n C : f o r e a r m a n d s u p p o r t b o a r d
( a r m b o a r d ) a n d e r g o n o m i c s t r a i n i n g
I n t e r v e n t i o
n D : f o r e a r m s u p p o r t b o a r d
( a r m b o a r d ) , t r a c k b a l l , a n d e r g o n o m i c s
t r a i n i n g
A m u s c u l o s k e l e t a l i n j u r y
p r e v e n t i o n p r o g r a m c o n s i s t i n g o f
m e c h a n
i c a l l i f t s a n d
r e p o s i t i o n i n g a i d s , a z e r o l i f t
p o l i c y ,
a n d w o r k e r t r a i n i n g o n
l i f t u s a g e
T y p e o f s t u d y
B e f o r e - a f t e r w i t h
c o n t r o l
B e f o r e - a f t e r u n c o n t r o l l e d
R a n d o m i z e d c o n t r o l l e d t r i a l
L o n g i t u d i n a l ( i n t e r r u p t e d t i m e
s e r i e s ) u n c o n t r o l l e d
M e a s u r e m e n t
t i m e p e r i o d
1 2 m o n t h s
1 4 4 m o n t h s
1 2 m o n t h s
N A
T y p e o f
e c o n o m i c
e v a l u a t i o n
C o s t - b e n e fi t a n a l y s i s
C o s t - b e n e fi t a n a l y s i s
C o s t - b e n e fi t a n a l y s i s
C o s t - b e n e fi t a n a l y s i s
P e r s p e c t i v e
E m p l o y e r
E m p l o y e r
E m p l o y e r
E m p l o y e r
K e y o u t c o m e
m e a s u r e s
V a l u e o f p r o d u c t i v i t y p e r y e a r
M e d i c a l c a r e c o s t s a s s o c i a t e d w i t h l o w - b a c k
p a i n c a s e s ; v a l u e o f l o s t w o r k t i m e d u e t o s i c k
l e a v e ( p r o d u c t i v i t y ) ; p r o d u c t i v i t y l o s s d u e t o
l o w - b a c k p a i n
a t w o r k ; a n d p r o d u c t i v i t y
e n h a n c e m e n t s d u e t o i n t e r v e n t i o n
W o r k e r s ’ c o m p e n s a t i o n e x p e n s e s
W o r k e r s ’
c o m p e n s a t i o n e x p e n s e s
( m e d i c a l a n d i n d e m n i t y
p a y m e n
t s ) r e l a t e d t o r e s i d e n t
h a n d l i n g i n j u r i e s
E c o n o m i c
e v a l u a t i o n
r e s u l t s
T h e b e n e fi t - c o s t r a t i o w a s 2 4 . 6 1
N e t s a v i n g s p e r y e a r w e r e $ 7 0 , 4 4 1 w i t h s a v i n g s
p e r w o r k e r o f $ 1 1 1 . T h e b e n e fi t - t o - c o s t r a t i o
w a s 8 4 . 9 a n d t
h e p a y b a c k p e r i o d w a s
0 . 5 m o n t h s ( 2 0
0 2 d o l l a r s )
T h e p a y b a c k p e r i o d w a s 1 0 . 6 m o n t h s ,
b a s e d o n
t h e a s s u m p t i o n t h a t t h e
i n c i d e n c e o f a c c e p t e d c l a i m s f o r n e c k /
s h o u l d e r
i n j u r i e s a m o n g c u s t o m e r s e r v i c e
o p e r a t o r s a t t h e c o m p a n y i s 0 . 0 1 4 4 a n d
t h e n e c k / s h o u l d e r i n j u r y r e d u c t i o n f r o m
t h e i n t e r v e n t i o n i s 4 9 % ( t a k e n f r o m t h e
e s t i m a t e d h a z a r d r a t e )
T h e p a y b
a c k p e r i o d w a s s l i g h t l y
l e s s t h a
n 3 y e a r s
D e t a i l s o f S t u d y
S c o r e ( o v e r a l l
s c o r e a n d
i n d i v i d u a l
i t e m s c o r e s )
O v e r a l l : 3 . 5 5 ( H i g h )
( 1 ) 4 ; ( 2 ) 5 ; ( 3 ) 3
. 5 ; ( 4 ) 4 ; ( 5 ) 4 ; ( 6 ) 4 ; ( 7 )
4 ; ( 8 ) 5 ; ( 9 ) 2 . 5
; ( 1 0 ) 4 ; ( 1 1 ) 3 . 5 ; ( 1 2 ) 1 ;
( 1 3 ) 3 ; ( 1 4 ) 2 . 5
O v e r a l l : 3 . 5 5 ( H
i g h )
( 1 ) 3 ; ( 2 ) 3 . 5 ; ( 3
) 3 ; ( 4 ) 2 . 5 ; ( 5 ) 3 ; ( 6 ) 2 ; ( 7 ) 4 ;
( 8 ) 3 ; ( 9 ) 4 ; ( 1 0 ) 5 ; ( 1 1 ) 3 ; ( 1 2 ) 5 ; ( 1 3 ) 4 ; ( 1 4 )
4 . 5
O v e r a l l : 2 . 8 ( M e d i u m )
( 1 ) 3 . 5 ; ( 2 )
4 ; ( 3 ) 4 ; ( 4 ) 4 ; ( 5 ) 4 ; ( 6 ) 3 ; ( 7 ) 4 ;
( 8 ) 2 ; ( 9 ) 2 ; ( 1 0 ) 1 ; ( 1 1 ) 1 ; ( 1 2 ) N A ; ( 1 3 )
1 ; ( 1 4 ) 2
. 5
O v e r a l l : 3 . 3 5 ( M e d i u m )
( 1 ) 5 ; ( 2 )
5 ; ( 3 ) 4 . 5 ; ( 4 ) 3 . 5 ; ( 5 ) 4 ;
( 6 ) 3 ; ( 7 ) 4 ; ( 8 ) 3 ; ( 9 ) 3 ; ( 1 0 ) 3 ;
( 1 1 ) 3 ;
( 1 2 ) 1 ; ( 1 3 ) 1 ; ( 1 4 ) 4
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T a b l e 4
c o n t i n u e d
S t u d y
B a n c o e t a l . [ 2
7 ]
D a l t r o y e t a l . [ 2 0 ]
V e r s l o o t e t a l . [ 2 1 ]
T u c h i n a n d P o l l a r d [ 2 2
]
E c o n o m i c
e v a l u a t i o n
r e s u l t s
E s t i m a t e d s a v i n g s f o r G r o u p A
s t o r e s w e r e $
2 4 5 p e r y e a r p e r
s t o r e a n d $ 2 9 , 4 1 3 p e r y e a r f o r
t h e c h a i n w h
e n c o m p a r e d t o t h e
s t a t u s q u o ( G
r o u p C s t o r e s ) .
B e n e fi t s f o r G r o u p B s t o r e s w e r e
l e s s d r a m a t i c
a n d t o t a l e d $ 1 0 6
p e r 1 0 0 , 0 0 0 m a n - h o u r s p e r s t o r e ,
w i t h t o t a l n e t s a v i n g s o f $ 1 2 , 7 7 3
f o r t h e c h a i n
T h e e f f e c t i v e n e s s o f t h e
i n t e r v e n t i o n w a s n
o t e s t a b l i s h e d ,
t h o u g h d e s c r i p t i v e
s t a t i s t i c s o f
e x p e n s e s w e r e p r e
s e n t e d . T h e
m e d i a n t o t a l e x p e n s e s p e r b a c k
i n j u r y w e r e $ 3 0 9 f o r t h e
i n t e r v e n t i o n g r o u p
, a n d $ 1 0 3 f o r
t h e c o n t r o l g r o u p .
G r o u p
a s s i g n m e n t ( i n t e r v
e n t i o n o r
c o n t r o l ) a n d t r a i n i n g s t a t u s w e r e
n o t s i g n i fi c a n t l y a s s o c i a t e d w i t h
c o s t . W o r k e r s w i t h a h i s t o r y o f
l o w - b a c k i n j u r y h a d h i g h e r
m e d i a n t o t a l e x p e n s e s , m e d i c a l
e x p e n s e s a n d p e r s
o n n e l -
r e p l a c e m e n t e x p e n s e s t h a n d i d
w o r k e r s w i t h o u t s u c h a h i s t o r y
I f t h e c h a n g e i n a b s e n t e e
i s m f o r t h e
i n t e r v e n t i o n g r o u p i s a s s e s s e d i n
r e l a t i o n t o t h e c h a n g e i n t h e c o n t r o l
g r o u p , t h e n t h e n e t p r e s e n t v a l u e i s
$ 1 0 3 , 4 0 0 . I f t h e c h a n g e i n a b s e n t e e i s m
i s a s s e s s e d o n l y w i t h i n
t h e i n t e r v e n t i o n
g r o u p , t h e n t h e n e t p r e s e n t v a l u e i s
$ 7 0 , 2 0 0
T h o u g h c o s t s a n d c o n s e q u e n c e s w e r e o n l y
c o n s i d e r e d s e p a r a t e l y , t h e i m p l i e d n e t p r e s e n t
v a l u e w a s $ 5 2 , 0 8 0 . T h e a u t h o r s m e n t i o n e d t h a t
t h e s a v i n g c o u l d b e i n e x c e s s o f $ 5 0 , 0 0 0 f o r a
3 - m o n t h p e r i o d
D e t a i l s o f S t u d y
S c o r e ( o v e r a l l
s c o r e a n d
i n d i v i d u a l i t e m
s c o r e s )
O v e r a l l : 2 . 5 ( M
e d i u m )
( 1 ) 4 ; ( 2 ) 4 ; ( 3
) 2 ; ( 4 ) 3 ; ( 5 ) 1 ; ( 6 )
2 ; ( 7 ) 3 ; ( 8 ) 4 ; ( 9 ) 2 ; ( 1 0 ) 3 ; ( 1 1 )
2 ; ( 1 2 ) 1 ; ( 1 3 ) 1 ; ( 1 4 ) 3
O v e r a l l : 3 . 6 ( H i g h )
( 1 ) 4 ; ( 2 ) 5 ; ( 3 ) 5 ; (
4 ) 5 ; ( 5 ) 4 ; ( 6 )
4 . 5 ; ( 7 ) 4 ; ( 8 ) 4 ; (
9 ) 3 ; ( 1 0 ) 2 ;
( 1 1 ) 2 ; ( 1 2 ) 1 ; ( 1 3
) N A / 1 ; ( 1 4 )
4 . 5
O v e r a l l : 3 . 3 5 ( M e d i u m )
( 1 ) 4 . 5 ; ( 2 ) 5 ; ( 3 ) 2 ; ( 4 ) 4
; ( 5 ) 4 ; ( 6 ) 4 ; ( 7 )
3 ; ( 8 ) 3 . 5 ; ( 9 ) 3 ; ( 1 0 ) 3
; ( 1 1 ) 3 ; ( 1 2 ) 1 ;
( 1 3 ) 3 ; ( 1 4 ) 4
O v e r a l l : 2 . 7 5 ( M e d i u m )
( 1 ) 3 . 5 ; ( 2 ) 4 . 5 ; ( 3 ) 2 ; ( 4
) 2 . 5 ; ( 5 ) 3 . 5 ; ( 6 ) 1 ; ( 7 ) 3 ;
( 8 ) 4 ; ( 9 ) 3 ; ( 1 0 ) 3 ; ( 1 1 ) 2 ; ( 1 2 ) N A ; ( 1 3 ) 1 ;
( 1 4 ) 3
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In the administrative and support services sector , two
intervention evaluations of high quality [12, 13], and one of
medium quality [10] were identified. From these studies we
concluded that there is moderate evidence that ergonomic
interventions in the administrative and support services
sector are worth undertaking on the basis of their financial
merits.
For the health care sector , there was also moderateevidence that ergonomic interventions are worth under-
taking for economic reasons. There were three medium
quality studies in this sector [14–16]. Two of the studies in
this group evaluated the introduction of mechanical patient
lifts, while the third evaluated the introduction of a par-
ticipatory ergonomics program.
Studies in the manufacturing and warehousing sector
provided strong evidence that ergonomic interventions are
worth undertaking for their financial merits.Therewere three
high quality studies (two in Lahiri et al. [13], and [17]) and
two medium quality ones [18, 19], and all concluded that the
ergonomic interventions were cost-effective in this sector.The last stratum with substantive evidence was the
transportation sector . This stratum provided limited evi-
dence that such interventions result in economic returns. In
this group there were three interventions. One was of high
quality [20] and found that the intervention was not
effective. Two medium quality studies [21, 22] found the
interventions to be cost-effective. Interestingly, these
interventions were all ergonomic education programs and
each was undertaken in a different country, namely the
Unites States, the Netherlands and Australia.
In all other sectors in which studies were identified there
was insufficient evidence on the cost-effectiveness of OHS
ergonomic interventions.
Across all sectors, there was a total of six high quality
studies and 10 medium quality ones. Of the sixteen studies,
all but one found the interventions to be worth undertaking
based on their financial merits. Consequently, when con-
sidering evidence across all sectors, we conclude that there
is strong evidence that ergonomic interventions result in
economic returns for the firm.
As noted, only four studies were participatory ergo-
nomic interventions. One of these was of high quality [17]
and three of medium quality [16, 18, 19]. This results in
moderate evidence that participatory ergonomic interven-
tions are worth undertaking based on their financial returns
for the company.
Summary of Studies in Sectors with Substantive
Evidence
The interventions in the administrative and support sector
targeted work station equipment and training for office
workers. Equipment included highly adjustable chairs,
lumbar pads and backrest and track ball and armboards
with computer use. Training included appropriate use of
equipment and back school workshops. Two studies had
more than one intervention arm including a control (both
also used regression modeling techniques to control for
confounders), while a third study was a before-after study
without a separate control. The three studies included in
this sector all undertook a cost-benefit analysis, and con-sidered insurance and productivity consequences.
In the health care sector, interventions included the
introduction of mechanical patient lifts in two cases and the
implementation of a participatory ergonomics team in the
other. The target populations were individuals working in a
hospital setting, such as nurses, nurses’ aides and orderlies.
Study designs were before-after without controls, two of
which used regression modeling techniques to control for
confounders. Regarding the economic evaluation method
employed, two studies undertook a cost-benefit analysis
while the other conducted a cost-consequence analysis (i.e.
costs and consequences are analyzed separately rather than jointly). Only insurance consequences were considered in
the economic analyses.
In the manufacturing and warehousing sector, the inter-
ventions focused on a broad range of MSK injury prevention
measures for individuals working with machinery. In three
cases the interventions were participatory, while in the other
two instances they consisted of engineering controls and
workstation modifications. All were before-after uncon-
trolled studies, with one using regression modeling tech-
niques to control for confounders. Four studies undertook a
cost-benefit analysis, and one was a partial analysis that only
considered insurance consequences.
The three studies identified in the transportation sector
were ergonomic education programs focused on back
injury prevention. All were randomized controlled trials
though not blinded. Regression modeling and analysis of
variance was undertaken to assess the difference between
and within groups. With regards to the economic evalua-
tion component, each study undertook a different type of
analysis. One study was a partial analysis, the second a
cost-consequence analysis and a third a cost-benefit anal-
ysis. Insurance and productivity consequences were con-
sidered. The intervention was not found to be effective in
one study, whereas it was in the other two.
Discussion
Evidence of Financial Merits of Ergonomic
Interventions
The research question addressed in this systematic review
was: ‘‘what is the credible evidence that incremental
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investment in ergonomic interventions is worth undertak-
ing?’’ Previous reviews have synthesized the evidence on
the effectiveness of office ergonomic interventions [3] and
of participatory ergonomic interventions [2]. However, this
systematic review is unique in that no other review has
examined the financial merits associated with ergonomic
interventions.
From the nine sectors identified, a definitive statementabout the level of evidence could be made in four industrial
sectors: administrative and support services sector, health
care sector, manufacturing and warehousing sector and
transportation. In the other five of the nine sectors, there
was insufficient evidence due to the small number of
studies and/or their low quality. As well, a synthesis of
studies across all sectors suggests strong evidence that
ergonomic interventions result in financial returns for the
firm. There were only four high and/or medium participa-
tory ergonomic interventions, so there was only moderate
evidence in support of the financial merits of these types of
interventions across all sectors.In the majority of the studies, intervention implemen-
tation was motivated by a high number of workplace
injuries. Related to this was a concern about workers’
compensation insurance and absenteeism costs, as these
may bear on business performance. These costs outcomes
were the two main economic outcomes examined in most
studies. All studies included in the synthesis took the
employer’s perspective, focusing on monetary costs and
consequences borne by the employer. The focus on only
one perspective and a limited set of outcomes was one of
the major shortcomings in this literature.
Methodological Recommendations
Two key methodological findings from the review are that:
(1) few ergonomic intervention studies undertake an eco-
nomic evaluation, and (2) the intervention studies that do
undertake economic analyses present a diversity of meth-
odological approaches and quality with a large number of
low quality studies. Other reviews of the OHS literature
have come to similar conclusions [23–25]. Indeed, a
common complaint in the assessments of the research lit-
erature on the economic evaluation of workplace inter-
ventions is that ‘well-designed and conducted evaluations
of programme costs and benefits were nearly impossible to
find’ [25]. Nonetheless, the review did identify a sufficient
number of high and medium quality studies to make sub-
stantive statements about the evidence in some industrial
sectors.
As noted, the quality assessment of studies was based on
a tool developed from previously completed research that
outlines key issues to consider in OHS economic evalua-
tions, and a methods text on good practice [8, 9]. Details on
study scores for each of the 14 quality assessment items
can be found in Table 4. Also included are other method-
ological details and the key outcomes considered in each
study. Although there were several high quality economic
analyses identified in the systematic review [12, 13, 17,
20], and a number of medium quality ones [10, 14–16, 18,
19, 21, 22, 26, 27], more than half of the intervention
studies identified were of low quality. This is likely due tothe focus in this literature on effectiveness rather than cost-
effectiveness. Also, undertaking economic evaluations of
OHS interventions can be difficult, and there is little
guidance available on how it should be done. Most meth-
ods texts are designed for use in a clinical setting, but a
number of factors in the workplace setting are different
than the clinical setting. Following is a list of key differ-
ences: (1) the policy arena of OHS and labor legislation is
complex, with multiple stakeholders and sometimes con-
flicting incentives and priorities; (2) there are substantial
differences in the perceptions of health risks associated
with work experiences amongst workplace parties, poli-cymakers and other OHS stakeholders; (3) there is a con-
sequential lack of consensus amongst stakeholders about
what, in principle, ought to count as a benefit or cost of
intervening or not intervening (this is an issue related to the
appropriate perspective to be taken in a study); (4) the
burden of costs and consequences may be borne by dif-
ferent stakeholders in the system; (5) there are multiple
providers of indemnity and medical care coverage, such
that no one measure accurately captures the full cost of
work-related injury and illness, nor conversely, the benefits
of their prevention; (6) industry-specific human resources
practices (e.g. hiring temporary workers and self-employed
contractors, outsourcing non-core activities) can make it
difficult to identify all work-related injuries and illnesses;
and (7) in general there is an absence of good guidelines
regarding costs and consequences combined with a dearth
of data available from organizations making it both chal-
lenging and expensive to obtain good measures. The above
list of reasons might explain why few studies of OHS
interventions contain an economic evaluation, and why the
quality of economic evaluations is usually poor.
Based on observation of the application of economic
evaluation methods in this literature, several recommen-
dations are offered to help improve future applications of
these methods. The recommendations are drawn from
across all the studies considered in this review, including
the low quality ones. For a more complete discussion of
methodological issues and recommendations we refer
readers to the following sources [6, 8, 9].
A number of studies identified undertook a ‘‘partial
economic analysis.’’ The phrase ‘‘partial economic analy-
sis’’ is used to describe studies that considered only con-
sequences in monetary terms, but did not consider
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intervention costs. With the exception of two studies [19,
20], such studies were not of sufficient quality to remain in
the evidence synthesis. Amongst the studies that consid-
ered both costs and consequences, many considered only a
limited subset. Furthermore, we sometimes found a dis-
connect between the effectiveness and economic evalua-
tions. Specifically, one set of analyses fed into the
effectiveness evaluation, and a separate set of analyseswere undertaken for the economic component. In some
cases, the two types of analyses not only relied on different
health outcome data, measurement and analytic time frame,
but also used different study designs, with economic
evaluation often employing a weaker design (e.g. before-
after without a concurrent control group and no statistical
adjustment for confounders). For many studies the eco-
nomic analysis was not the principal focus of the investi-
gation, and for some it was a very small component.
Another concern is that studies employed different
approaches to the computation and analysis of costs and
consequences, making it difficult to compare results acrossstudies. For example, some studies with cost and conse-
quences in monetary terms used net present value, others
the payback period, yet others a cost-benefit ratio. We
would suggest a standard approach to computations, a type
of reference case as suggested by Gold et al. [28] and
Tompa et al. [9].
Most studies that undertook economic analyses focused
on work absence costs (primarily wage costs or workers’
compensation wage replacement costs) and medical care
costs. One concern with using workers’ compensation
claims costs as the sole or primary outcome measure is that
it does not capture the full set of costs and consequences,
even from a firm’s perspective. A range of indirect costs
may be incurred by a firm that results in costs substantially
larger than the direct absence costs. A common approach in
many studies taking the firm perspective was to use the
insurer’s claim expenses in the cost-benefit analysis.
However, in some jurisdictions workers’ compensation
insurance provided by an insurer are experience rated, and
the losses borne by the insurer are not fully offset by
premium increases to the injury employer. A fraction of the
costs may be pooled across all firms in a particular rate or
risk group. If a firm is self insured, then the full cost of a
claim is borne by the employer. Only one study we iden-
tified made an adjustment for this fact [17]. Furthermore,
workers’ compensation claims do not reflect the full extent
of work-related injuries and illnesses. Many workplace
injuries and illnesses go unreported, and others are not
compensable [29]. Researchers need to consider other
measures of health and their associated costs, either
through primary data collection or exploitation of other
administrative data sources (e.g. first aid reports, modified
duty, and private indemnity claims).
Many of the high- and medium-quality studies under-
took cost-benefit analysis, and used some variant of a
human capital approach (a measure of productivity) to
value absence time. Several studies went further in their
assessment of productivity implications and considered
at-work productivity changes due to the intervention.
Although financial outcomes and productivity issues may
be of primary interest to most firms, the value of health toother stakeholders, particularly injured workers and their
families includes much more. Missing in this measure is
the intrinsic value of good health to workers and the value
of health associated with the ability to better perform in
other social roles.
The perspective taken matters for the workplace mea-
sures of health used in an evaluation. In fact, the per-
spective bears on all the costs and consequences considered
in an economic evaluation. All studies included in the
synthesis took the firm perspective, considering only those
costs and consequences experienced by the firm. There is a
strong case to be made for considering other perspectives,particularly those of the worker and system or society, as
well as for a disaggregation of the costs and consequences
by stakeholder in order to better understand their compo-
sition and distribution.
A number of standard computational practices were also
overlooked in some analyses. For example, when the costs
and/or consequences of an intervention are realized over
more than a year, one should adjust for inflation and time
preference. Data on inflation rates are readily available
from most national statistical agencies. To adjust for time
preference, discounting is required for both costs and
consequences, even if consequences are not measured in
dollars. Many jurisdictions stipulate the discount rate at
which public sector investments are to be discounted. For
the private sector, firms may have their own specific rate
used for project investments. The real discount rates (net of
inflation) commonly used in the literature are 3 and 5%
[30]. Thus, we suggest considering both rates in an anal-
ysis, and possibly undertaking a sensitivity analysis using a
range of rates. In fact, sensitivity analysis should be
undertaken with all key assumptions to test the robustness
of results to these assumptions.
Strengths and Weaknesses of the Review
One of the key strengths of this study is its broad scope.
Evidence on the financial merits of ergonomic interven-
tions of different types and across all sectors was consid-
ered. The literature search was quite thorough. A number
of journal databases were considered and included, and a
detailed and lengthy search strategy was used to ensure all
relevant studies were captured. Another strength is the
inclusion of a stakeholder advisory group from the early
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stages of the review process. The advisory group provided
feedback on the question guiding the review and the
framing of the topic, literature search scope, synthesis
stratification, presentation of individual study data and
evidence synthesis findings. The stakeholder advisory
group represented the primary target audiences for the
evidence synthesis, and therefore ensured that the final
product met all stakeholders’ information needs.One potential review limitation is that the gray literature
was not included. The stakeholder advisory group had
initially suggested including the gray literature. They felt
strongly that the lack of evidence on the financial merits of
OHS interventions, and the importance of this information
to them, warranted a broad sweep of the literature.
Although the gray literature may have been a potential
source for relevant evaluations, the published literature
itself was quite vast and not well catalogued for retrieving
studies with economic evaluations. The identification of
almost 13,000 titles and abstracts made for a daunting first
stage of study identification, and adding a gray literaturesearch would have made the task unmanageable with the
resources available. Another concern was the quality of the
gray literature. Though the quality of each study considered
for inclusion in the synthesis was evaluated, the peer
review process of academic journal publication provided a
rigorous first level of assessment, which would not be
present with the gray literature, and therefore might require
a different, more extensive quality assessment process. A
downside of including only peer reviewed studies is that
there may be a positive publication bias, i.e. studies with
statistically insignificant findings in terms of effectiveness
and cost-effectiveness may be less likely to be published.
Indeed, most studies identified reported positive findings.
Another limitation is that the search was restricted to
studies written in English. This may have precluded
potentially relevant publications in other languages. As
noted many of the included studies were undertaken in the
US (ten in total), although the synthesis did include two
studies undertaken in Europe, two in Australia and two in
Canada. Future research on this topic might include pub-
lications in languages other than English and assess the
evidence implications of including studies in multiple
languages compared to English language literature only.
Conclusion
This review found strong evidence supporting the eco-
nomic merits of ergonomic interventions in the manufac-
turing and warehousing sector, moderate evidence
supporting the economic merits of such interventions in the
administrative and support services sector, and health care
sectors and limited evidence in the transportation sector.
The review highlights the need for a more systematic
consideration of the financial merits of ergonomic inter-
ventions and a further development of standardized ana-
lytic methods in order to ensure a larger and more reliable
evidence base on the financial merits of such interventions.
It is recommended that all researchers who are considering
evaluating a workplace intervention seriously consider
including an economic evaluation.The findings are of value to workplace parties, OHS
practitioners and policymakers who are interested in
knowing what interventions are worth undertaking from a
financial viewpoint. The findings are also of value to OHS
researchers, who might seek to fill some of the gaps in the
literature and strive to improve the quality of future eco-
nomic evaluations. Undoubtedly, the knowledge of the
financial merits of an ergonomic intervention is critical to
employers, insurers and policymakers, so it is to the det-
riment of the value of an intervention evaluation study to
leave economic analysis out of the evaluation plan.
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