The physical exertion factor in compensable work injuries. A hidden flaw in previous research.

Studies of the industrially injured worker invariably suggest that compensation reinforces pain and prolongs disability. These claims may be spurious. Researchers have historically failed to take into account the fact that return to work is partly contingent on the amount of physical labor involved in the job, and that compensation and noncompensation groups differ on this variable in important ways. Patients on compensation are more likely involved in heavy physical exertion on their jobs. In this study, 1,191 workers with low-back pain who were injured on the job were compared with 389 workers who were injured away from work on variables of disability time and pain intensity. To disentangle the effects of physical exertion, four levels ranging from none to heavy were examined. The results suggest that injury on the job operates both independent of level of physical exertion, as well as in interaction with it, to extend the period of disability. Injury on the job is associated with prolonged disability time, irrespective of the type of job performed.