Early Predictors of Occupational Back Reinjury: Results From a Prospective Study of Workers in Washington State

Study Design. Prospective population-based cohort study. Objective. To identify early predictors of self-reported occupational back reinjury within 1 year after work-related back injury. Summary of Background Data. Back injuries are the costliest and most prevalent disabling occupational injuries in the United States. A substantial proportion of workers with back injuries have reinjuries after returning to work, yet there are few studies of risk factors for occupational back reinjuries. Methods. We aimed to identify the incidence and early (in the claim) predictors of self-reported back reinjury by approximately 1 year after the index injury among Washington State workers with new work disability claims for back injuries. The Washington Workers' Compensation Disability Risk Identification Study Cohort provided a large, population-based sample with information on variables in 7 domains: sociodemographic, employment-related, pain and function, clinical status, health care, health behavior, and psychological. We conducted telephone interviews with workers 3 weeks and 1 year after submission of a time-loss claim for the injury. We first identified predictors (P < 0.10) of self-reported reinjury within 1 year in bivariate analyses. Those variables were then included in a multivariate logistic regression model predicting occupational back reinjury. Results. A total of 290 (25.8%) of 1123 (70.0% response rate) workers who completed the 1-year follow-up interview and had returned to work reported having reinjured their back at work. Baseline variables significantly associated with reinjury (P < 0.05) in the multivariate model included male sex, constant whole-body vibration at work, previous similar injury, 4 or more previous claims of any type, possessing health insurance, and high fear-avoidance scores. Baseline obesity was associated with reduced odds of reinjury. No other employment-related or psychological variables were significant. Conclusion. One-fourth of the workers who received work disability compensation for a back injury self-reported reinjury after returning to work. Baseline variables in multiple domains predicted occupational back reinjury. Increased knowledge of early risk factors for reinjury may help to lead to interventions, such as efforts to reduce fear avoidance and graded activity to promote recovery, effective in lowering the risk of reinjury.