The effect of health insurance coverage on the use of medical services

Substantial uncertainty exists regarding the causal effect of health insurance on the utilization of care. We exploit a sharp change in insurance coverage rates that results from young adults "aging out" of their parents' insurance plans to estimate the effect of insurance coverage on the utilization of emergency department (ED) and inpatient services. Aging out results in an abrupt 5 to 8 percentage point reduction in the probability of having health insurance. We find that uninsured status leads to a 40 percent reduction in ED visits and a 61 percent reduction in inpatient hospital admissions