Association of Medicaid Accountable Care Organizations and postpartum mental health care utilization

To examine the association of Massachusetts Medicaid Accountable Care Organization (ACO) implementation with changes in mental health care utilization in the postpartum period. We examine care for people with a birth covered by Medicaid or private insurance. We used a difference-in-differences design to compare differences before and after Medicaid ACO implementation for those with Medicaid versus those with private insurance. The primary outcome was a binary measure of having at least one outpatient mental health care visit in the 6 months postpartum. We estimated linear probability models controlling for age, prenatal mental illness, pregnancy complications, birth mode, and ZIP code characteristics. Data are from the Massachusetts All-Payer Claims Database. The analytic sample included Massachusetts residents with a live birth between July 1, 2016, and September 30, 2019, with complete data. 107,813 births were included (53.0% Medicaid, 47.0% private). 7.8% of these had at least one outpatient mental health visit in the 6 months postpartum, with similar rates among those with Medicaid versus those with private insurance pre-ACO implementation (7.9% Medicaid versus 7.7% private). An increase in utilization among privately insured individuals and a decrease among Medicaid beneficiaries post-ACO implementation was observed. Regression-adjusted difference-in-differences estimates indicate that Medicaid ACO implementation was associated with a 1.3 percentage point [pp] decrease (95% confidence interval: 1.3 pp, -0.5 pp; p