STUDY DESIGN: Five-year prospective cohort study of 1449 transit operators. OBJECTIVES: To investigate psychosocial job factors as predictors of work-related spinal injuries, controlling for current and past physical workload. SUMMARY OF BACKGROUND DATA: The association between psychosocial job factors and spinal disorders may be confounded by physical workload. A 1991 prospective study of Boeing workers found psychosocial but not physical factors to be associated with spinal injuries. However, data on physical workload were limited. Recent cross-sectional studies of transit drivers showed both physical and psychosocial factors to be independently associated with back and neck pain. This study was designed to test these findings prospectively. METHODS: Spinal injuries were ascertained from workers' compensation records, employment history from company records, and psychosocial factors from questionnaires. 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. Spinal 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 with a 2.7-fold reduced risk for spinal injury (OR, 0.37; 95% CI, 0.15-0.93). Cable car crews performing the heaviest physical labor had a threefold increased 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 independently predict spinal injury in transit vehicle operators.
STUDY DESIGN: Five-year prospective cohort study of 1449 transit operators. OBJECTIVES: To investigate psychosocial job factors as predictors of work-related spinal injuries, controlling for current and past physical workload. SUMMARY OF BACKGROUND DATA: The association between psychosocial job factors and spinal disorders may be confounded by physical workload. A 1991 prospective study of Boeing workers found psychosocial but not physical factors to be associated with spinal injuries. However, data on physical workload were limited. Recent cross-sectional studies of transit drivers showed both physical and psychosocial factors to be independently associated with back and neck pain. This study was designed to test these findings prospectively. METHODS:Spinal injuries were ascertained from workers' compensation records, employment history from company records, and psychosocial factors from questionnaires. 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. Spinal 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 with a 2.7-fold reduced risk for spinal injury (OR, 0.37; 95% CI, 0.15-0.93). Cable car crews performing the heaviest physical labor had a threefold increased 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 independently predict spinal injury in transit vehicle operators.