Impact of the Affordable Care Act Medicaid Expansion on Utilization of Mental Health Care.

Background: The Affordable Care Act's Medicaid expansions (ME) increased insurance coverage for low-income Americans, among whom unmet need for mental health care is high. Empirical evidence regarding the impact of expanding insurance coverage on use of mental health services among low income and minority populations is lacking.
Methods: Data on mental health service use collected between 2007 and 2015 by the Medical Expenditures Panel Survey from nationally representative cross-sectional samples of low income (income<138% of the federal poverty line) adults were analyzed. Use trends among people in states that expanded Medicaid (ME states; n=29,827) were compared with concurrent trends among people in states that did not (non-ME states; n=22,873), with statistical adjustment for demographic characteristics and psychological distress.
Results: Annual outpatient visits for mental health conditions increased by 0.513 (0.053-0.974) visits per person, from a baseline rate in ME states of 0.894 visits per person. However, no significant changes were observed in number of mental health related hospital stays, emergency department visits or prescription fills. The increase outpatient visits was limited to Hispanics and non-Hispanic Whites, with no increase in service use observed among non-Hispanic Blacks. There was no apparent increase in the number of users of outpatient mental health care (AOR=0.992, P=0.942) and a marginally significant (P=0.096) increase of 3.144 visits per user.
Discussion: ME had a limited but positive impact on use of mental health services by low income Americans, although it may also have increased racial/ethnic disparities.