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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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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?

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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

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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


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


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


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


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




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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