The effect of health insurance on medical care utilization and implications for insurance expansion: a review of the literature.

Both the costs and benefits associated with extending health insurance coverage depend on the extent and exact ways in which health insurance affects the utilization of medical care. We review the literature relating to such effects with the goal of informing researchers interested in simulating the impact of policy initiatives aimed at achieving universal coverage. Overall, this literature is quite consistent in finding significant effects of insurance on all types of utilization. Insurance coverage increases outpatient utilization by roughly 1 visit per year for children and between 1 and 2 visits for adults. For both children and adults, these visits are associated with an increased receipt of preventive care. Insurance coverage also increases inpatient utilization for children and adults; for children, there is some evidence that insurance coverage reduces ambulatory care sensitive hospital admissions.