The effect of health insurance on health care utilization and health outcomes

In light of the substantial increase in adult Medicaid coverage brought about by the Affordable Care Act (ACA), there is great interest in understanding the effect of such coverage on access to health care services and on health outcomes.  A large literature studying the effects of earlier public insurance expansions for children finds significant positive effects on the utilization of health care services as well as on morbidity and mortality.  However, much less is known about the health effects of expanding Medicaid eligibility for adults. 

 In this paper we study pre-ACA Medicaid expansions targeted at parents, estimating the effect of these expansions on perceived access to care, actual health care utilization and self-reported health status.  The analysis is based on data from the Behavioral Risk Factor Surveillance System (BRFSS), spanning the years 1998 to 2010, a period when a number of states expanded Medicaid eligibility for parents.  The BRFSS provides information on insurance coverage, the utilization of a number of different health care services and several measures of self-reported health.  Our basic empirical model estimates the relationship between these outcomes and a state’s parental Medicaid income eligibility threshold, conditional on individual characteristics and state and year fixed effects.

We find that state parental Medicaid expansions during this period significantly increased insurance coverage, with implied take-up rates similar to those found in prior studies using other data sources.  This increased coverage coincided with a decrease in the percentage of low-income adults reporting that there was a time in the last year when they needed to see a doctor but could not because of the cost and an increase in the percentage saying that they had a personal doctor.  When we stratify the data by gender, we find that the significant effect of state Medicaid eligibility expansions on the probability of having a personal doctor is limited to women.  We also find that a state’s Medicaid income eligibility threshold is positively and significantly related to the probability that a woman had a pap test and mammogram in the past year.  For both men and women, increases in a state’s eligibility threshold lead to improvements in self-reported physical and mental health.