Multifactor association of job, individual and psychosocial factors in prevalence of distal upper extremity disorders and quantification of job physical exposure

Abstract

The objective of this study was to develop a multifactor model of job, individual and psychosocial factors in prevalence of distal upper extremity musculoskeletal disorders (DUE MSDs); and quantify job physical exposure to establish safe exposure limits. The study sample comprised of 525 workers who were part of a large prospective cohort study and represented a broad array of industrial practices and a wide range of job physical exposure. Only baseline data was considered for the analysis in the study. Workers underwent laptop administered questionnaires, structured interviews, two standardized physical examinations and nerve conduction studies to ascertain demographic, medical history, psychosocial factors and current DUE MSDs. All workers' jobs were individually measured for job physical exposure factors and videotaped. Binomial logistic regression was used to develop and test the multifactor association and quantification of job physical exposure for safe exposure limits. Results indicated that work-related DUE MSDs are multifactor in nature and are significantly affected by specific factors of (1) job physical exposure - percentage duration of exertion (PDOE), workers' subjective ratings of perceived effort or intensity of exertion (IOE) (using Borg CR-10), hand activity level measured by the American conference of Governmental Industrial Hygienists (ACGIH) threshold limit value for hand activity level (TLV for HAL), and presence of 2-point pinch grasps; (2) individual factors - female gender, diabetes, higher body mass index (BMI), and past and current smokers; (3) psychosocial factors - neither likely/unlikely or very unlikely to take up the current job again, divorced/separated, and presence of family problems. Quantification of job physical exposure indicated that prevalence of work-related DUE MSDs significantly increases with efforts per minute (Eff/min) >8 (OR = 1.69, p = 0.006) and woker's perceived effort based on Borg rating for IOE at the end of the shift >3 (OR = 2.46, p < 0.001). Further studies should be conducted to validate these safe exposure limit criteria.