Association for Public Policy Analysis & Management

Prior to the implementation of the primary components of the ACA in 2014, there were well documented disparities in insurance coverage along multiple dimensions, such as age, race, income, family structure, and geography. The primary components of the ACA, including the individual mandate, subsidized Marketplace coverage, and state Medicaid expansions, were designed to reduce health insurance coverage disparities by moving the U.S. closer to universal coverage. The purpose of this paper is to examine the extent to which the ACA reduced disparities in coverage after three years (2014-2016). In order to uncover the causal impact of the ACA on coverage disparities, we follow Courtemanche et al. (2017, 2018a, 2018b) by estimating difference-in-difference-in-differences (DDD) models where the differences come from time, state Medicaid expansion decisions, and pre-ACA local area uninsured rates. Much of the previous literature focuses on the effects of the ACA Medicaid expansions alone using simpler difference-in-differences (DD) models comparing changes over time between Medicaid expansion and non-expansion states. In contrast, we also identify the impact of the national portion of the ACA (combination of insurance regulations, mandates, and subsidized Marketplace coverage) by leveraging the propensity for universal coverage initiatives to provide the most intense “treatment” in local areas with the highest pre-reform uninsured rates. Changes in coverage disparities are evaluated by stratifying our sample by income, race/ethnicity, marital status, age, gender, and geography. We estimate these DDD models use data from the American Community Survey (ACS) between 2011 and 2016. The ACS includes multiple categories of insurance coverage, allowing us to evaluate how the ACA affected coverage disparities via changes to both private and public coverage.

Our results suggest that the fully implemented ACA reduced the coverage disparity between those with incomes below 138 percent of the FPL and those with incomes over 400 percent FPL by 14 percentage points, or 43 percent of the pre-ACA gap. This entire reduction is attributable to the Medicaid expansion, which targeted low income childless adults. We also find that the fully implemented ACA reduced coverage disparities between whites and non-whites by 23 percent, between married and unmarried individuals by 46 percent, and between young adults and older nonelderly adults by 36 percent. Both the Medicaid expansion and nationwide components of the ACA contributed to these reductions, which highlights the importance of broadening the scope of analysis beyond the Medicaid expansion alone. In contrast, results for the other stratifications were less notable. The full ACA led to similar increases in coverage among women and men and therefore did not alter the tendency for women to have a higher coverage rate. Additionally, although rural individuals are generally considered a vulnerable population when it comes to health care access, the pre-ACA uninsured rate was only slightly higher for those living in rural as opposed to urban areas. The ACA more than completely eliminated this small gap.