Medicaid enrollment increased significantly post-Affordable Care Act—progress that could be reversed by program changes
In the decade since the Affordable Care Act (ACA) expanded eligibility criteria for Medicaid, enrollment in the program rose significantly among certain groups, according to a new study by Harvard T.H. Chan School of Public Health researchers. The researchers noted that this progress toward a more widely insured population may be reversed by potential changes to Medicaid being considered by federal lawmakers.
The study, published May 13 in the Milbank Quarterly, was co-authored by Rebecca Smith, a former research assistant at Harvard Chan School; Benjamin Sommers, Huntley Quelch Professor of Health Care Economics; and Gabriella Aboulafia, a student in the Harvard PhD Program in Health Policy.
The researchers used data from the American Community Survey and state-level eligibility criteria to assess Medicaid enrollment among U.S. adults younger than 65 who either had Medicaid coverage or no insurance. They focused on enrollment between 2008, before passage of the ACA, and 2023, the year of Medicaid “unwinding,” when states reevaluated their Medicaid rolls after COVID-era expansions to the program expired.
The study found that Medicaid enrollment among eligible individuals increased from 76.5% pre-ACA to 85% post-ACA. By 2023, when pandemic expansions were rolled back, Medicaid enrollment was even slightly higher, at 86.5%. Children, Asian Americans, Black Americans, and residents of expansion states—states that, under the ACA, offered Medicaid to more of their populations—saw their enrollment rates increase the most. Young adults ages 19-21, Native Americans, employed adults, and those whose Medicaid coverage would come with premiums saw their enrollment increase the least. The researchers also found that Medicaid enrollment increases were higher in urban than rural communities.
According to the researchers, the findings have important implications for the future of Medicaid. Despite the significant post-ACA increases in Medicaid enrollment, “many eligible individuals remain uninsured, particularly young adults, childless adults, and people living in non-expansion states,” they wrote. “Future efforts should aim to increase coverage in these groups, but reductions in outreach, increased use of premiums, or a rollback of ACA provisions could threaten the past decade’s gains in coverage for millions of Medicaid enrollees.”
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