1998 Volvo Award winner in clinical studies - Psychosocial job factors, physical workload, and incidence of work-related spinal injury: A 5-year prospective study of urban transit operators

Study Design. Five-year prospective cohort study of 1449 transit operators. Objectives. To investigate psychosocial job factors as predictors of work-r elated spinal injuries, controlling for current and past physical workload. Summary of Background Data. The association between psychosocial job factor s and spinal disorders may be confounded by physical workload. A 1991 prosp ective study of Boeing workers found psychosocial but not physical factors to be associated with spinal injuries. Recent cross-sectional studies of tr ansit drivers showed both physical and psychosocial factors to be independe ntly associated with back and neck pain. This study was designed to test th ese findings prospectively. Methods. Spinal injuries were ascertained from workers' compensation record s, employment history from company records, and psychosocial factors from q uestionnaires. Logistic regression models adjusted for age, gender, height, weight, vehicle type, and current and past physical workload. Results. During follow-up, 320 drivers reported a first spinal injury. Spin al injury was predicted by psychological job demands (odds ratio [OR], 1.50 ; 95% confidence interval [CI], 1.33-1.95); job dissatisfaction (OR, 1.56; 95% CI, 1.09-2.23); and the frequency of job problems (OR, 1.52; 95% CI, 1. 02-2.26). Marginally significant associations were found for low supervisor support (OR, 1.30; 95% CI, 0.99-1.72) and female gender (OR, 1.49; 95% CI, 0.95-2.32). Compared with full-time work, part-time work was associated wi th a 2.7-fold reduced risk for spinal injury (OR, 0.37; 95% CI, 0.15-0.93). Cable care crews performing the heaviest physical labor had a threefold in creased risk of spinal injury compared with bus drivers (OR, 3.04; 95% CI, 1.85-5.00). Conclusions. Physical workload and psychosocial job factors both independen tly predict spinal injury in transit vehicle operators.