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Conclusions
The steering committee has explored the complex problem of musculoskeletal disorders in the workplace. We have supplemented our professional expertise with workshop presentations, commissioned papers and other submissions, and discussions with invited workshop participants. We find very clear signals on some topics and weaker signals on others-but little in the way of contradiction. Thus, while there are many points about which we would like to know more, there is little to shake our confidence in the thrust of our conclusions, which draw on converging results from many disciplines, using many methods:
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There is a higher incidence of reported pain, injury, loss of work, and disability among individuals who are employed in occupations where there is a high level of exposure to physical loading than for those employed in occupations with lower levels of exposure.
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There is a strong biological plausibility to the relationship between the incidence of musculoskeletal disorders and the causative exposure factors in high-exposure occupational settings.
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Research clearly demonstrates that specific interventions can reduce the reported rate of musculoskeletal disorders for workers who perform high-risk tasks. No known single intervention is universally effective. Successful interventions require attention to individual, organizational, and job characteristics, tailoring the corrective actions to those characteristics.
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Research can (1) provide a better understanding of the mechanisms that underlie the established relationships between causal factors and outcomes so that workers who are at risk can be identified and interventions undertaken before problems develop; (2) consider the influence of multiple factors (mechanical, work, social, etc.) on symptoms, injury, reporting, and disability; (3) provide more information about the relationship between incremental change in load and incremental biological response as a basis for defining the most efficient interventions; (4) improve the caliber of measurements for risk factors, outcome variables, and injury data collection and reporting systems; and (5) provide better understanding of the clinical course of these disorders.
By and large, the controversies that we observed reflect the usual disputatiousness of science, which advances when speculative challenges lead to new and clarifying results. One feature of the discourse around musculoskeletal disorders is that it sometimes involves individuals from one discipline (or sub-discipline) who reject entirely the legitimacy of research from another. The steering committee understands the claims made by these often forceful advocates of particular research ideologies. However, we respect the contributions of properly designed research conducted by the variety of disciplines needed for the topic.
The steering committee's task has been to examine the state of the evidence. As such, we have tried to assess the plausible ranges of effects for the various factors that have been studied systematically. We have, however, deliberately avoided providing recommendations for action for three reasons:
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The risk of musculoskeletal disorders depends on the interaction of person and task, as does the effectiveness of options for reducing those risks. A full specification would require much more detailed treatment of person-task combinations than is possible here. We have, instead, focused on the scientific principles that should guide the prediction and prevention of problems.
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We have not reviewed the full range of consequences of musculoskeletal disorders and interventions related to them. For example, we have not evaluated the effects of ergonomics programs on employee productivity, turnover, and morale. Nor have we examined the effects of musculoskeletal disorders on the economic and psychological well-being of injured individuals and their families. Rational decision making must consider the full set of relevant consequences.
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Rational decision making also depends on the relative importance attached to the different consequences. Different people and institutions will have different values and different opportunities for action, at the governmental, employer, and individual levels.