Effects of the Affordable Care Act Medicaid Expansion on the Distribution of New General Internists Across States.

Background: Some states expanded Medicaid under the Affordable Care Act, boosting their low-income residents' demand for health care, while other states opted not to expand.

Objective: The objective of this study was to determine whether the Medicaid expansion influenced the states selected by physicians just completing graduate medical education for establishing their first practices.

Research Design: Using 2009-2019 data from the American Medical Association Physician Masterfile and information on states' Medicaid expansion status, we estimated conditional logit models to compare where new physicians located during the 6 years following implementation of the expansion to where they located during the 5 years preceding implementation.

Subjects: The sample consisted of 160,842 physicians in 8 specialty groups.

Results: Thirty-three states and the District of Columbia expanded Medicaid by the end of the study period. Compared with preexpansion patterns, we found that physicians in one specialty group-general internal medicine-were increasingly likely to locate in expansion states with time after the expansion. The Medicaid expansion influenced the practice location choices of men and international medical graduates in general internal medicine; women and United States medical graduates did not alter their preexpansion location patterns. Simulations estimated that, between 2014 and 2019, nonexpansion states lost 310 general internists (95% confidence interval, 156-464) to expansion states.

Conclusions: The Medicaid expansion influenced the practice location choices of new general internists. States that opted not to expand Medicaid under the Affordable Care Act lost general internists to expansion states, potentially affecting access to care for all their residents irrespective of insurance coverage.