Did the ACA Medicaid Expansion Affect Physician Participation in Medicaid?

The Affordable Care Act (ACA) has extended Medicaid coverage to low-income adults in 32 states, resulting in an unprecedented increase in the prevalence of Medicaid coverage. Research suggests that those newly covered by Medicaid in expansion states were more likely to see a primary care physician and were more likely to report a usual source of care in expansion states relative to non-expansion states. Despite an increase in patient reports of better access, little work has described the impact of the expansion on actual physician participation in the program. Understanding such changes is important because of recent claims that Medicaid beneficiaries have poor access to medical providers and because of a perceived primary care physician shortage. We used administrative data on physician practices in the United States to estimate the change in self-reported appointment availability for Medicaid patients before and after Medicaid expansion, comparing practices in Medicaid expansion and non-expansion states. Our preliminary results show mixed evidence that primary care practices increased Medicaid appointment availability in states that expanded Medicaid relative to states that did not.