Objectives This study followed 279 auto assembly workers over 1 year to identify which factors influenced whether a worker would visit the plant medical department because of an upper-extremity musculoskeletal problem.

Methods Incident cases were defined as involving workers who had not gone to the plant medical department in the preceding 6 months and then subsequently visited the medical department with a work-related musculoskeletal disorder that was potentially due to repetitive work activity (acute fractures or lacerations were excluded).

Results There were 45 cases identified during the study period. Based on Cox regression analysis, significant predictors for visiting a medical department included exceeding the threshold limit value for hand activity and peak force, a history of diabetes, a current diagnosis of carpal tunnel syndrome, elbow tendonitis, and age under 40 years.

Conclusions The results of this study are consistent with those of other prospective studies that showed that both ergonomic and past medical history are risk factors for an upper-extremity musculoskeletal disorder and suggests that there is a healthy worker or survivor effect among older workers.

Key terms Cox regression; cumulative trauma disorder; medical department; MSD; musculoskeletal disorder; occupational medicine; repetitive strain injury; risk factor; upper extremity