The Affordable Care Act of 2010 provided states with federal funding to expand their Medicaid programs to cover all adults with incomes up to 138% of the federal poverty, but a Supreme Court decision rendered the coverage expansion optional. Of the fourteen remaining states that opted not to expand their Medicaid programs, nine are in the South. Along with researchers at Vanderbilt University School of Medicine, associate professor of health care policy (biostatistics) Laura A. Hatfield, PhD, professor of health care policy and medicine Nancy L. Keating, MD, MPH, and Warren Alpert Foundation Professor of Health Care Policy J. Michael McWilliams, MD, PhD, investigated the impact of Medicaid expansions in the South on the health of low-income adults by comparing changes in health in expansion states and non-expansion states in a recent study published in Health Affairs.

Examining self-reported health data from 15,356 low income individuals, the study found lower rates of physical and mental health decline in the expansion states than in non-expansion states in the South.

“The effect is sizable, analogous to the worst-ranked southern state rising about halfway up the rankings in state population health if it expanded Medicaid,” McWilliams told HMS News. “Unlike many other studies, we were able to focus on some of the most vulnerable populations who stand to gain the most from insurance coverage.”

The study examined a population of adults served by community health clinics. The health benefits of Medicaid expansion found by the researchers therefore suggest that the health care safety net for the uninsured is not a substitute for insurance coverage. The team concluded that state decisions to forego the federal support and opt not to expand Medicaid has likely harmed the health of chronically ill low-income residents.