Abstract
INTRODUCTION: Preventive and primary care in the postpartum year is critical for future health and may be increased by primary care focused delivery system reform including implementation of Medicaid Accountable Care Organizations (ACO). This study examined associations of Massachusetts Medicaid ACO implementation with preventive visits in the postpartum year. METHODS: The Massachusetts All-Payer Claims Database was used to identify births to privately-insured or Medicaid ACO-eligible individuals from January 1, 2016 to February 28, 2019. Comparing these groups before and after implementation, a propensity score weighted difference-in-difference design was used to analyze associations of Medicaid ACO implementation with any preventive care visit and any primary care physician (PCP) preventive visit within one year postpartum, controlling for other characteristics. Analyses were performed in 2023 and 2024. RESULTS: Of the 110,601 births in the study population, 35.5% had any preventive care visit and 23.0% had any preventive PCP visit in the year postpartum, with higher rates of preventive visits among privately-insured individuals. In adjusted difference-in-difference analyses, relative to the pre-period, there was a 2.7 percentage point (pp) decrease (95% confidence interval [CI]: -4.3pp, -1.2pp) and 3.5 pp decrease (95% CI: -4.9pp, -2.0pp) in use of any preventive visits and any PCP preventive visits, respectively, for Medicaid-insured versus privately-insured individuals after ACO implementation. CONCLUSIONS: Implementation of Massachusetts Medicaid ACOs was associated with decreases in receipt of preventive visits and preventive PCP visits for Medicaid-insured individuals relative to privately-insured individuals. Medicaid ACOs should consider potential implications of primary care access in the postpartum year for health across the lifecourse.