Background: Several states have expanded Medicaid eligibility for adults in the past decade, and the Affordable Care Act allows states to expand Medicaid dramatically in 2014. Yet the effect of such changes on adults' health remains unclear. We examined whether Medicaid expansions were associated with changes in mortality and other health-related measures.
Methods: We compared three states that substantially expanded adult Medicaid eligibility since 2000 (New York, Maine, and Arizona) with neighboring states without expansions. The sample consisted of adults between the ages of 20 and 64 years who were observed 5 years before and after the expansions, from 1997 through 2007. The primary outcome was all-cause county-level mortality among 68,012 year- and county-specific observations in the Compressed Mortality File of the Centers for Disease Control and Prevention. Secondary outcomes were rates of insurance coverage, delayed care because of costs, and self-reported health among 169,124 persons in the Current Population Survey and 192,148 persons in the Behavioral Risk Factor Surveillance System.
Results: Medicaid expansions were associated with a significant reduction in adjusted all-cause mortality (by 19.6 deaths per 100,000 adults, for a relative reduction of 6.1%; P=0.001). Mortality reductions were greatest among older adults, nonwhites, and residents of poorer counties. Expansions increased Medicaid coverage (by 2.2 percentage points, for a relative increase of 24.7%; P=0.01), decreased rates of uninsurance (by 3.2 percentage points, for a relative reduction of 14.7%; P<0.001), decreased rates of delayed care because of costs (by 2.9 percentage points, for a relative reduction of 21.3%; P=0.002), and increased rates of self-reported health status of "excellent" or "very good" (by 2.2 percentage points, for a relative increase of 3.4%; P=0.04).
Conclusions: State Medicaid expansions to cover low-income adults were significantly associated with reduced mortality as well as improved coverage, access to care, and self-reported health.