HMOs, moral hazard and cost shifting in workers' compensation.

Previous research has shown that workers respond to the economic incentives provided in workers' compensation. In particular, claim frequency rises with increased benefits, and claim duration, on net, seems to increase. Here we provide additional evidence of another incidence of behavioral responses to incentives. We find that doctors in health maintenance organizations (HMOs) have a greater tendency to classify claims as compensable under workers' compensation than do other physicians. Our evidence suggests that the rapid expansion of HMOs over the 1980-1990 period resulted in a significant increase in workers' compensation claim frequency.