MUSCULOSKELETAL DISORDERS AND THE WORKPLACE:
LOW BACK AND UPPER EXTREMITIES
Dr. Jeremiah A. Barondess, M.D.
Chairman of the Panel on Musculoskeletal Disorders and the Workplace
National Research Council/Institute of Medicine
President, New York Academy of Medicine
Subcommittee on Employment, Safety and Training
Committee on Health, Education, Labor and Pensions
July 18, 2001
Good morning, Mr. Chairman and members of the Committee. My name is Dr. Jeremiah Baroness. I am the President of the New York Academy of Medicine and Chairman of the Panel on Musculoskeletal Disorders and the Workplace.
The Panel on Musculoskeletal Disorders and the Workplace was established by the National Research Council (NRC) and the Institute of Medicine (IOM) in January, 1999, to conduct a two-year study of the contribution of workplace physical and psychosocial factors to the occurrence of musculoskeletal disorders of the low back and upper extremities and to examine the effectiveness of various prevention strategies. The panel is composed of 19 experts representing the fields of biomechanics, epidemiology, hand surgery, human factors engineering, internal medicine, nursing, occupational medicine, orthopedics, physical medicine and rehabilitation, physiology, psychology, quantitative analysis, and rheumatology.
The impetus for the study was a request from Congress (including your subcommittee) to examine the causation, diagnosis, and prevention of musculoskeletal disorders (House Report 105-635). The congressional request was presented in the form of seven questions. The charge to the panel, prepared by the NRC and the IOM, was stated as a series of tasks designed to provide a comprehensive review of the science base and to address the issues outlined in the congressional questions. A complete statement of the panel’s charge, approach, conclusions, and recommendations is found in the first attachment: the Executive Summary of the final report. Attachment App. A provides the panel’s response to the congressional questions.
The panel approached the complex of factors bearing on the risk of musculoskeletal injury in the work setting from a whole-person perspective, that is, from a point of view that does not isolate disorders of the low back and upper extremities from physical and psychosocial factors in the workplace, from the context of the overall texture of the worker’s life, including social support systems at work and in the community and physical and psychosocial stresses outside the workplace, or from personal responses to pain and individual coping mechanisms. The focus of the study was on work-related factors. Individual factors and activities outside of the workplace were considered as context and were accounted for in the literature reviews. Our task was to determine the incremental effect of work-related factors on the occurrence of musculoskeletal disorders.
The panel applied a set of rigorous scientific criteria in selecting the research studies for its review. Because the literature includes both empirical and theoretical approaches and covers a wide variety of research designs, measurement instruments, and methods of analysis, the quality selection criteria varied somewhat among disciplines. At one level, there are highly controlled studies of soft tissue responses to specific exposures using cadavers, animal models, and human subjects. At another level, there are surveys and other observational epidemiologic studies that examine the association among musculoskeletal disorders and work, organizational, social, and individual factors. At yet another level, there are experimental and quasi-experimental studies of human populations designed to examine the effects of workplace interventions. Studies at each level have attendant individual strengths; each also has limitations when considered in isolation. When taken together however, they provide a rich basis for understanding the causes and prevention of musculoskeletal disorders.
Dimensions of the Problem
The first conclusion reached by the panel is that musculoskeletal disorders of the low back and upper extremities are an important national health problem, resulting in approximately 1 million people losing time from work each year. These disorders impose a substantial economic burden in compensation costs, lost wages, and productivity. Conservative cost estimates vary, but a reasonable figure is about $50 billion annually in work-related costs--a figure representing approximately 1 percent of GDP.
The panel found that estimates of incidence in the general population, as contrasted with the working population, are unreliable because more than 80 percent of the adult population in the United States is in the workforce. Nevertheless, the magnitude of the problem of work-related musculoskeletal disorders can be gleaned from the Bureau of Labor Statistics data. These data suggest that musculoskeletal disorders are a problem in multiple industrial sectors; they are not limited to the traditional heavy labor environments represented by agriculture, mining, and manufacturing. It was reported, for example, that the service sector is also importantly involved, accounting for 26 percent of sprains/strains, carpal tunnel syndrome, or tendinitis; the manufacturing sector accounted for 22 percent. Another data base, National Center for Health Statistics, using self reports, provided estimates for back pain among those whose pain occurred at work (approximately 11.7 million) and for those who specifically reported that their pain was work-related (5.6 million). In this survey, the highest-risk occupations among men were construction laborers, carpenters, and industrial truck and tractor equipment operators; among women, the highest-risk occupations were nursing aides/orderlies/attendants, licensed practical nurses, maids, and janitor/cleaners. Other high-risk occupations were hairdressers and automobile mechanics.
Relationship Among Work Factors and Musculoskeletal Disorders
A second major conclusion is that the weight of the evidence justifies the identification of certain work-related risk factors for the occurrence of musculoskeletal disorders of the low back and upper extremities.
• The panel concludes that there is a clear relationship between back disorders and physical load; that is, manual material handling, load moment, frequent bending and twisting, heavy physical work, and whole-body vibration. For disorders of the upper extremities, repetition, force, and vibration are particularly important work-related factors. That is, physical workplace activities have been shown to be responsible for a significant increment in the occurrence of musculoskeletal disorders of the low back and upper extremities.
• Work-related psychosocial factors recognized by the panel to be associated with low back disorders include rapid work pace, monotonous work, low job satisfaction, low decision latitude, and job stress. High job demands and high job stress are work-related psychosocial factors that are associated with the occurrence of upper extremity disorders.
The Value of Workplace Interventions
A third major conclusion is that the weight of the evidence justifies the introduction of appropriate and selected interventions in the workplace to reduce the risk of musculoskeletal disorders of the low back and upper extremities. These include, but are not confined to, the application of ergonomic principles to reduce physical as well as psychosocial stressors. To be effective, intervention programs should include employee involvement, employer commitment, and the development of integrated programs that address equipment design, work procedures, and organizational characteristics.
There is no generic solution. To be effective interventions must be tailored to the specific work and worker conditions and must be evaluated on a continuing basis to account for changing workplace and worker factors.
Cost and effectiveness of various intervention strategies are a major concern for public and private policy makers, managers, and other leaders facing the practical challenges of allocating limited resources. Despite the availability of cost benefit analysis techniques they have not been systematically applied to the study of workplace interventions designed to relieve or prevent musculoskeletal disorders. Outcome measures generally include relief from pain and loss of function and reductions in worker’s compensation claims and time away from work. Although there are individual studies that demonstrate favorable outcomes following the introduction of an intervention, the conditions under which the data are collected make it difficult to determine which of several specific factors are responsible for the outcome. On the other side of the equation are the costs associated with the design and implementation of the interventions. Some interventions require minor changes in procedures or layouts for specific work spaces while others may involve developing large-scale design modifications or instituting new work practices or ways to organize work. Here again, some scattered individual studies exist. What is needed to resolve these issues is careful research to develop a methodology to facilitate both cost and benefit comparisons across alternative interventions in a range of workplaces.
The Need for Data Collection and Reporting Systems
To extend the current knowledge base relating both to risk and effective interventions, the Bureau of Labor Statistics should continue to revise its current data collection and reporting system to provide more comprehensive surveillance of work-related musculoskeletal disorders. Specific attention should be given to revising the illness and injury coding system, refining the quantification of risk, and developing denominator data for job-specific demographic features. Reporting should also be enhanced to include details on musculoskeletal disorders that do not involve lost workdays. Enhanced resources are needed to address these recommendations.
The National Center for Health Statistics and the National Institute for Occupational Safety and Health should include measures of work exposures and musculoskeletal disorder outcomes in ongoing federal surveys (e.g., the National Health Interview Surveys, the National Health and Nutritional Examinations), and NIOSH should repeat, at least decennially, the National Occupational Exposure Survey. NIOSH should develop both a passive surveillance packages for use by a broad range of employees and a model for an active surveillance program for interested employers.
The National Institute for Occupational Safety and Health should take the lead in developing uniform definitions of musculoskeletal disorders for use in clinical diagnosis, epidemiologic research, and data collection for surveillance systems. These definitions should (1) include clear and consistent endpoint measures, (2) agree with consensus codification of clinically relevant classification systems, and (3) have a biological and clinical basis.
A Research Agenda
The panel recommends a research agenda that includes developing (1) improved tools for exposure assessment, (2) improved measures of outcomes and case definitions for use in epidemiologic and intervention studies, and (3) further quantification of the relationship between exposures and outcomes. Also included are suggestions for studies in each topic area: tissue mechanobiology, biomechanics, psychosocial stressors, epidemiology, and workplace interventions. In addition, the panel recommends (1) expanding research and research training, (2) promoting collaboration among industry, labor, and academia, and (3) expanding education and training in utilizing workplace interventions to employers. In order to accomplish these objectives, the panel recognized that funding for NIOSH would have to be significantly increased. Broader support for these research programs should also be sought from relevant NIH Institutes.
The conclusions and recommendations provided in the panel’s report were supported by 18 of the 19 panel members. The dissenting member, a hand surgeon, prepared a statement that was limited to a very narrow concern--the relationship between carpal tunnel syndrome and keyboarding. Unfortunately, he uses this case to question the scientific basis for the panel’s review and interpretation of all of the literature. Essentially, he asserts that because the relationship between low force, high repetition activities and muscusloskeletal disorders is weak, the relationship between any work and the occurrence of a musculoskeletal disorder may not be sound.
Some key points in the dissent assert that the panel used an unscientific approach to the literature review, that it over-reached in interpreting the literature on the relationship between keyboarding and carpal tunnel syndrome, and that it recommends ergonomics as an exclusive remedy for musculoskeletal disorders. All of these assertions are countered in the panel’s response to the dissent (see Attachment App. C). It is important to note that many of the research studies cited by the dissenting member in his discussion of the epidemiology of carpal tunnel syndrome and work did not meet the rigorous review criteria established by the panel and were rejected for inclusion in the full report. Furthermore, one of the 18 panel members is a leading and highly regarded hand surgeon and an enthusiastic supporter of the panel’s conclusions and recommendations.
Mr. Chairman, I want to thank you for the opportunity to provide testimony on this important topic. I will be happy to answer any questions.