Musculoskeletal Disorders and the Workplace Low Back and Upper Extremities (2001) / Chapter Skim
Currently Skimming:
Epidemiological Evidence
Epidemiological Evidence
Pages 85-183
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 85... ...
· The participation rate was 70 percent or more. · Health outcomes relate to musculoskeletal disorders of the low back, neck, and upper extremities and were measured by well-defined criteria determined before the study.
|
From page 86... ...
The advantages of prospective studies, however, were recognized. For example, there were sufficient prospective studies of low back pain to examine these separately among the studies of physical factors and exclusively among the studies of psychosocial factors.
|
From page 87... ...
, other measures, such as the prevalence ratio and the odds ratio, have been developed to summarize the association between exposure and outcomes for these other study designs. Our analysis focused on associations expressed by such risk estimates as the odds ratio and the relative risk.
|
From page 88... ...
Consequently, we have not attempted to rank or further interpret the findings for attributable fractions and have chosen only to report them as a rough guide to the relative importance of the factors in the study settings in which they have been examined. In this review, the relative risk in longitudinal studies and the prevalence or odds ratio in cross-sectional surveys were used to calculate the attributable fraction for the risk factors studied.
|
From page 89... ...
Personal characteristics and other environmental and socio-cultural factors usually play a role as risk factors in work-related diseases, which are often more common than occupational diseases" (World Health Organization, 1985~. In Chapter 3 we note that the epidemiologic study of causes related to health outcomes such as musculoskeletal disorders requires careful attention to the several factors associated with the outcome.
|
From page 90... ...
The role of potential confounders in epidemiologic studies and their proper management is often confusing to the nonepidemiologist. The difficulty stems from the fact that the potential confounder is often known to be associated with the disease, in this case musculoskeletal disorders.
|
From page 91... ...
are associated with the outcome (musculoskeletal disorders) and the two risk factors are also correlated (for example, those with more work exposure are also older)
|
From page 92... ...
In some studies, absolute ratings have agreed well with observations or direct measurements of the corresponding exposures, while others have diverged significantly, especially with use of continuous estimates or responses that required choices among a large number of categories (e.g., Burdorf and Laan, 1991; Faucett and Rempel, 1996; Lindstrom, Ohlund, and Nachemson, 1994; Rossignol and Baetz, 1987; Torgen et al., 1999; Viikari-Juntura, 1996; Wiktorin et al., 1993~. Retrospective recall of occupational exposures has been frequently employed in studies of musculoskeletal disorders, but there are few data on the reproducibility of such information.
|
From page 93... ...
. For example, the goniometer has been used in a variety of studies of wrist posture, including field assessments of ergonomic risk factors (Moore, Wells, and Ranney, 1991; Wells et al., 1994)
|
From page 94... ...
. The strain index is a single priority score designed to represent risk for upper extremity musculoskeletal disorders and is conceptually similar to the lift index for low back disorders.
|
From page 95... ...
These surveys are typically presented to subjects in a paper format in which the subject is requested to complete a series of questions. These survey tools typically comprise multiple scales used to assess psychosocial risk factors.
|
From page 96... ...
Measures of Musculoskeletal Disorder Outcomes The epidemiologic literature on the relationship between exposure to physical and psychosocial risk factors and the development of musculoskeletal disorders in the workplace focuses on four major types of outcome. Two outcomes rely on patient self-report (symptoms and work status)
|
From page 98... ...
These risk factors were found significant in almost all of the studies: lifting and/or carrying of loads in 24 of the 28 in which it was studied, whole-body vibration in 16 of the 17, frequent bending and twisting in 15 of the 17, and heavy physical work in all 8 in which this factor was studied. The following significant findings are summarized from these studies: for lifting and/or carrying of loads, risk estimates varied from 1.1 to 3.5, and attributable fractions were between 11 and 66 percent; for whole-body vibration, risk estimates varied from 1.3 to 9.0, with attributable fractions between 18 and 80 percent; for frequent bending and twisting, risk estimates ranged from 1.3 to 8.1, with attributable fractions between 19 and 57 percent; and for heavy physical
|
From page 99... ...
for manual material handling and frequent bending and twisting. An explaTABLE 4.2 Summary of Epidemiologic Studies with Risk Estimates of Null and Positive Associations of Work-Related Risk Factors and the Occurrence of Back Disorders Risk Estimate Null Associationa Positive Association Attributable Fraction (%)
|
From page 100... ...
However, the case-control study with the highest risk estimate was based on observations at the workplace. In general, risk estimates in community-based surveys (Appendix Table 4.2)
|
From page 101... ...
, depending on how specifically the exposure and the outcome were defined. With the exception of the few studies of bone- and joint-related abnormalities, most of the results demonstrate a significant positive association between upper extremity musculoskeletal disorders and exposure to repetitive tasks, forceful tasks, the combination of repetition and force, and the combination of repetition and cold.
|
From page 102... ...
, conditions classified as "wrist cumulative trauma disorders" or "nonspecific upper extremity musculoskeletal disorders" were found to be significantly associated with work-related physical risk factors with a similar range of elevated risk. Hand-arm vibration syndrome and other vibration disorders were significantly associated with vibration exposures in 12 of 13 studies, with risk elevated 2.6 to 84.5 times that of nonexposed or low-exposed comparison workers.
|
From page 103... ...
In two, significant associations were found with pain or discomfort in the upper extremity, and the third found association with slowed median nerve velocity in subclinical carpal tunnel syndrome. The attributable fractions related to the physical risk factors that were found to be important provide additional useful information.
|
From page 104... ...
Psychosocial Factors Psychosocial risk factors for work-related musculoskeletal disorders can be separated into two major categories: those that are truly specific to the workplace (job satisfaction, poor social support at work, work pace, etc.) and those that are individual psychosocial factors (such as depression)
|
From page 105... ...
n n Range High job demands 1 Low decision latitude/control 0 Low stimulus from work (monotony) 2 Low social support at work 0 Low job satisfaction High perceived stress High perceived emotional effort Perceived ability to return to work Perceived work dangerous to back 5 2 2 4 7 13 6 o o o o 3 1 21-48 23 28-48 1 7-69 17 NOTE: Details on studies are presented in Appendix Table 4.7.
|
From page 106... ...
Individual Psychosocial Factors The results demonstrate that individual psychosocial factors are related to back pain from its inception to the chronic stage (Table 4.5 and Appendix Table 4.8~. Indeed, these variables were shown to be important in the development of pain and disability.
|
From page 107... ...
Although psychological factors are considered to be of particular importance in chronic pain, the data reviewed show distinctly that psychosocial factors are also pivotal in the transition from acute to chronic pain as well as being influential at onset. Moreover, the results suggest that psychosocial factors are not simply an overlay, but rather an integral part of a developmental process that includes emotional, cognitive, and behavioral aspects.
|
From page 108... ...
Second, if psychosocial elements play a central role in back pain, then better interventions could be designed to deal with these factors to provide better care and prevention. Summary of Work-Related and Individual Psychosocial Factors Based on the studies reviewed here, there is ample evidence that both work-related and individual psychosocial factors are related to subsequent episodes of back pain (Tables 4.4 and 4.5; Appendix Tables 4.7 and 4.8~.
|
From page 109... ...
The attributable fractions related to work-related psychosocial risk factors suggest that improvement in job satisfaction may reduce risk for back disorders by 17 to 69 percent, while improved social support at work might reduce risk by 28 to 48 percent. Acknowledging the limitations associated with the interpretation of attributable fractions (as discussed earlier in the chapter)
|
From page 110... ...
Considering all upper extremity sites, this table indicates that the number of studies reporting a positive association for high job demands, high perceived stress, and nonwork-related worry and distress was greater than those reporting no significant effect for these exposures. This table also indicates that a number of potential psychosocial risk factors were not shown to be associated with the onset of work-related upper extremity symptoms or disorders.
|
From page 111... ...
Elbow/Arm High job demands Low decision latitude; low control and low stimulus from work Low social support Low job satisfaction High perceived job stress 1 1.4 Few rest break opportunities Low support nonwork-related Worry, tension, psychological distress, nonwork-related 1.5-1.9 3 33-47 37-47 1.6-1.9 3 5 o 3 1 3.3 o 1 3 1.1 5 1.0-3.0 5 2 1.2-1.7 1 70 4.8 - 79 l 2.0-2.4 2 50-58 2.8 1 64 o o 2 2.0 1 50 1 3.1 1 67 o 1 1 0 - 1 1.4-1.8 3.1 1 28-44 continues
|
From page 112... ...
The attributable fractions related to these risk factors suggest that modification of the high job demands could potentially reduce the risk for upper extremity disorders and symptoms by 33 to 58 percent. Reduction in perceived levels of job stress could reduce the risk for upper extremity disorders and symptoms by 50 percent, and reduction in nonwork-related worry, tension, and distress has the potential to reduce risk by 28 to 79 percent.
|
From page 113... ...
These findings highlight the importance of conducting additional studies to identify specific factors that contribute to the identified risk factors and to explain how these interact to influence the development, exacerbation, or maintenance of work-related upper extremity disorders. It is also important to determine how these psychosocial factors interact with medical and ergonomic risk factors to modify risk.
|
From page 114... ...
Most studies reviewed here also show a meaningful strength of association measured by both estimates of the relative risk and calculation of attributable risk. The attributable risk provides an estimate of the proportion of musculoskeletal disorders that might be prevented if effective interventions were implemented; the calculations are appreciable for most for the exposures summarized here.
|
From page 115... ...
This review indicated the utter lack of studies that were found to be of sufficient quality and that examine both physical and psychosocial factors together. Because evaluation of each has shown important effects on the development of musculoskeletal disorders, and some of the current evidence (although modest)
|
From page 116... ...
~ ~ a of ~ ~ · .
|
From page 117... ...
Appendix
|
From page 118... ...
118 ~ o .= ·~ ·5o ~ ¢ o U o u ~ O ~ be 5- o ~ ¢ ~ V)
|
From page 120... ...
120 o ¢ Em X ¢ ~ o ~ u o' ~ ~ ~ 5-1 §1 ~ 5- ,24 o Co CD o u o o o :^ En 5o ¢ ~ ~ ~ ¢ o' o' o' o' o' ON Cal ~ ~ CO 00 00 CO 00 ~ ~ ~ ON ~ ~ ~ O .
|
From page 123... ...
123 U ~~ C o U ~ o 5 - ~ U ~ O cd ~L, U O US ~ o o Flu ~ ~ ¢ · ~ U o o · o ~ .
|
From page 125... ...
125 ._, o C 5- ~L, ~ o U O o ·~ ~L, u ~ O o u be o .V)
|
From page 128... ...
128 CD o .~ .~of .n ~ ~ In ¢ Em X ¢ o ~ ¢ ¢ ¢ ¢ ¢~m u o o o o CO o o o o o o o o Lr)
|
From page 134... ...
134 o ¢ EN X ¢ o u CD o o o in 5o x e A ~ O ~ ~ ~ ~ ~ ~ ~ ~ X e 5 o o V ¢ co O cn ~ ~ it, ~ ~ ,U ~ ~ ~ ~ O ~ o O o u ~ o c C E D C O A E 5 ° ~ e ~ ,~ As, _ ~ A ~ 1 _1 , if, U ~ ~ ~ ~ ~ ~ ~ O ' ~ A ~ ~ ~ ~ D ?
|
From page 136... ...
136 o ¢ Ed X ¢ o u ~ o §1 ~ o ~ CD o o o En 5o CD O o C A ^ 0> u Us -` A e _ ° c O _ _ ~ ~ u u o A ~ ~ a o u to tn ~ ~ A ,,, — ~ i, ~ ~ U ~ ~ O To 5- ~ 5 3 ~ A E ~ ~ ~ ~ ~ ~~ ~ X ~ ~ ~ U 5 ° ~ ~ ~ ~ o ~ En o o ~ C C Lo ~ A E ~ Co o o ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ON ON co ON ' ON ·_1 .$ ~ ~ ~ ~ .
|
From page 138... ...
138 o ¢ EM X ¢ o u ~ o o ~ CD o u ·_1 ^' En I ~ ~ o ° ~ ~ =^ ~ ~ ~ o ~ =$ in ~ ~~ O — 0N No Ed CL~ ~ L)
|
From page 143... ...
143 So ~ ~ ~ 2 ~ ~ ~ C ~ C ~ -A U ~ ~ U o U o o ~ ~ ~ o ~ ° o ~ o ~ ~ ~ ,24 MU ~ ~ ~ ~ ~ ~ ·m ·Co ~ ~ o ~ ~ ~ ~ lo, X V u ~ ~ ~ ~ ~ ~ ~ o ~ A o O _ _ ~ ,24 O ~ ~ ~ ~ ~ ~ ~ O .O Co ~~ U .~ ~ ~ o ~ ~ O ~ TO U r0 C ~ ~ ~ ~ ~ ~ ~ ~ o ~ ~ ~ D _ C 44 0 5_, ~ ~ ~ _ 1 1 ° ~~¢ ~ ~ E ~ C ~ fi ~ ~ a, ~ ~ ~ ~ in in CD :^ ,24 ~ ~ ~ o c ~ ~ ~ ~ ~ 2 ~ ~ ~ 'D ~ ~ > ~ '
|
From page 147... ...
147 E A' fi ~m D u ~ O ~ ~ ~ ~ ~ U ~ ~ O ED ~ .> U ,~ O 50- ~ ~ O o ° ..
|
From page 148... ...
148 o ._, u o o no.
|
From page 149... ...
149 ~ o CD Co m~ ~ ~ ~ E A ~ ~ c,, ~ o ~ i- c,, o o u =^ -~ ~ C =o C ~ ~ o ° =- E U Do oo ~ U ~ ·m CD CD CD i~ ~ ~ E =~ e D E ¢ ~ ~ ¢ Cal r _ _ t~d ~~ )
|
From page 150... ...
150 o Do ¢ EM X ¢ o o CD CD o o U ¢ ~ .m 5U o co mu so ~ U^,24 CD · CD o u o o o cn ~ 5o , ~ 5 0 ~ o e , ~ 2 ~ , O ' ~ ~ ~ .- ~ =~ ~ cn ~ ~ cn ~ ¢ ~ CD CD ·_1 ~ · - ~ U O MU O O ~ O 0~ 00 .
|
From page 152... ...
152 o Do ¢ EM X ¢ o o CD CD o o U ¢ ~ .m 5U o co mu so ~ U^,24 CD · CD o u o o o cn ~ 5o in ~ ~ ~ ~ ,~ o ,24 ~ ~ ~ U o o A, ~ ~ ~ 2 ~ ~ ~ ~ ~ ~ o C o ~ ~ ~ ~ C ~ o hi 'D ~ Cal ~ o o ~ co co ~ #_ En 0 50- ~ 50- Co ~ no .
|
From page 154... ...
154 o Do ¢ Ed X ¢ o o CD CD o o U ¢ .m 5U o co Mu so ~ U^,24 CD · CD o u o o o En ~ 5o .
|
From page 156... ...
156 o oo ¢ Em X ¢ o a CD CD o o U ¢ ~ .m 5U o co Mu so ~ U^,24 CD · CD o u a o o En ~ 5o ~ ~ ~ ~ ~ ~ ~ ~ ~ X ~ 3 ~ 3 ~ ~ 5 ~= e ~ ~~ c En ~ ~ ~ CD ~ ~ .~= ;m ;~^ 5°- ~ 5°- Do 50- Do ¢ ¢ ~ _ _ lo c ~ ~ 5 ~ ~ i o ~ ~ u ~ ~ ~ ~ u ~ ~ ~ _ En ~ ~ ~ ~ :^ o ~ [e C ~ a, ~ En C ~ C ~ C ~ C [d En V , ' 0 , ·_1 · - ~ · - ~h
|
From page 157... ...
157 ~ ~ U X .~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~ ~~ a O ~ O o ~ ~ En ~ ~ ~ co En ~ ~ ~ En ~ ~ CD 5- CD O ~ CU - ` ~ ~ O ~ ~ Q1 ~ O Q1 ~ aim ~ aim ~ ~ ~0 ~ .
|
From page 158... ...
158 o oo ¢ Ed X ¢ o o CD CD o o U ¢ ~ .m 5U o Co YOU so ~ U^,24 CD · CD o u o o o in ~ , ~ o ' ~ ~ Z v co 5 ,,, A.=, 3 ~ ID ~ o ~ ..
|
From page 161... ...
161 O ~ ON O ON Cal Lr Lr)
|
From page 167... ...
167 - a or Lr)
|
From page 169... ...
169 - o on 1 Lr) to to v 1 ~1 o ~ o hate m>°~° ~ ~ ~ ~ ~ o ~ o U)
|
From page 173... ...
173 - o o~ or o o o~ o~ ~ o Lr)
|
From page 174... ...
174 o ¢ Ed X ¢ ho YOU ¢ ~ l l l l FLU => 'l CD CD CD CD 5- 5- 5- 5 == CD o o o o ~ zz ~ ~ CD 5o u CD u o CD so u :^ CD CD o u o o :^ ~ ~ o En ~ ~ En ~ 5, D ~ = , , ' ~ , ' E mu: ~ ~ .
|
From page 178... ...
178 o ¢ Em X ¢ ~ o 5- U ,~ ¢ ~ CD o u a o :^ ~ o En ~ 5o ¢ 1 1 ~ ~ ~ pa o o o o o~ o~ o~ o~ Do ~ Lr)
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.