Journal of Electromyography and Kinesiology 14 (2004) 13–23 www.elsevier.com/locate/jelekin Work-related musculoskeletal disorders: the epidemiologic evidence and the debate Laura Punnett à , David H. Wegman University of Massachusetts Lowell, One University Avenue, Lowell, MA 01854, USA Abstract The debate about work-relatedness of musculoskeletal disorders (MSDs) reflects both confusion about epidemiologic principles and gaps in the scientific literature. The physical ergonomic features of work frequently cited as risk factors for MSDs include rapid work pace and repetitive motion, forceful exertions, non-neutral body postures, and vibration. However, some still dispute the importance of these factors, especially relative to non-occupational causes. This paper addresses the controversy with refer- ence to a major report recently commissioned by the US Congress from the National Research Council (NRC) and Institute of Medicine (IOM) (2001). The available epidemiologic evidence is substantial, but will benefit from more longitudinal data to better evaluate gaps in knowledge concerning latency of effect, natural history, prognosis, and potential for selection bias in the form of the healthy worker effect. While objective measures may be especially useful in establishing a more secure diagnosis, subjective measures bet- ter capture patient impact. Examination techniques still do not exist that can serve as a ‘‘gold standard’’ for many of the symp- toms that are commonly reported in workplace studies. Finally, exposure assessment has too often been limited to crude indicators, such as job title. Worker self-report, investigator observation, and direct measurement each add to understanding but the lack of standardized exposure metrics limits ability to compare findings among studies. Despite these challenges, the epidemiologic literature on work-related MSDs—in combination with extensive laboratory evi- dence of pathomechanisms related to work stressors—is convincing to most. The NRC/IOM report concluded, and other review- ers internationally have concurred, that the etiologic importance of occupational ergonomic stressors for the occurrence of MSDs of the low back and upper extremities has been demonstrated. # 2003 Elsevier Ltd. All rights reserved. Keywords: Epidemiology; Ergonomics; Exposure assessment; Interaction; Multiple risk factors; Musculoskeletal disease; Review; Work-related 1. Introduction ‘‘Musculoskeletal disorders’’ include a wide range of inflammatory and degenerative conditions affecting the muscles, tendons, ligaments, joints, peripheral nerves, and supporting blood vessels. These include clinical syndromes such as tendon inflammations and related conditions (tenosynovitis, epicondylitis, bursitis), nerve compression disorders (carpal tunnel syndrome, sciati- ca), and osteoarthrosis, as well as less well standardized conditions such as myalgia, low back pain and other regional pain syndromes not attributable to known pathology. Body regions most commonly involved are the low back, neck, shoulder, forearm, and hand, although recently the lower extremity has received more attention. Musculoskeletal disorders (MSDs) are widespread in many countries, with substantial costs and impact on quality of life. Although not uniquely caused by work, they constitute a major proportion of all registered and/or compensable work-related diseases in many countries. Accurate data on the incidence and preva- lence of musculoskeletal disorders are difficult to obtain, and official statistics are difficult to compare across countries. Nevertheless, MSDs are the single lar- gest category of work-related illness, representing a third or more of all registered occupational diseases in the United States, the Nordic countries, and Japan [6,49,54,73]. Numerous surveys of working populations have reported upper extremity symptom prevalences of 20 to 30% or even higher. In the United States, Canada, Finland, Sweden, and England, musculoskele- à Corresponding author: Tel.: +1-978-934-3269 or -3250; fax: +1- 978-452-5711. E-mail address: laura_punnett@uml.edu (L. Punnett). 1050-6411/$ - see front matter # 2003 Elsevier Ltd. All rights reserved. doi:10.1016/j.jelekin.2003.09.015