Personal, biomechanical, psychosocial, and organizational risk factors for carpal tunnel syndrome: a structural equation modeling approach.

This longitudinal study aimed at exploring the direct and indirect relationships between organizational, psychosocial, biomechanical, and personal factors and carpal tunnel syndrome (CTS) in French workers. Between 2002 and 2005, 3710 workers were included in the Cosali cohort. Between 2007 and 2010, 1611 workers were re-examined using the same standardized clinical protocol. Subjects free from CTS at baseline were studied (804 men and 563 women). We used structural equation models to examine the relationships between incident CTS cases and organizational (machine-paced work or work pace dependent on customers' demand), psychosocial (job strain model), biomechanical (Borg's rating perceived exertion, wrist bending, pinching, and hand-transmitted vibrations), and personal factors at baseline. Symptomatic CTS risk was directly increased by biomechanical factors (standardized coefficient = 0.19, P = 0.011), female gender (0.25, P < 0.001), and age (0.15, P = 0.042). No psychosocial factors had a direct impact on CTS, but decision authority and skill discretion had an indirect impact by influencing biomechanical exposure. Exposure to machine-paced work had an indirect impact on increasing CTS, either by raising biomechanical exposure (0.19, P < 0.001) or by lowering decision authority (-0.18, P < 0.001) and skill discretion (-0.20, P < 0.001), which in turn increased biomechanical exposure. Similar complex relationships were observed between risk factors and CTS defined by a more strict case definition. Biomechanical exposure had a direct impact on CTS, while organizational factors and psychosocial factors had an indirect impact on CTS. The findings support conceptual models linking work organization to CTS.