Postpartum Linkage to Primary Care Among Patients With Diabetes and Hypertensive Disorders of Pregnancy Following Medicaid ACO Implementation

Background: Timely postpartum linkage to primary care is important for managing diabetes and hypertensive disorders of pregnancy (HDP), yet linkage remains suboptimal. Medicaid accountable care organizations (ACOs) aim to strengthen care coordination and improve postpartum linkage, although effects may vary by ACO design. Objective: Evaluate whether Massachusetts Medicaid ACO implementation was associated with changes in postpartum primary care linkage among enrollees with diabetes or HDP and whether effects differed by ACO model. Design: Retrospective cohort study using the 2016–2023 Massachusetts All-Payer Claims Database (APCD). Using a difference-in-differences approach, we compared outcomes before (2016–2017) versus after (2018–2023) implementation among health system/managed care partnership ACOs, primary care-led ACOs, and non-ACO enrollees. Subjects: In total, 38,340 Medicaid-covered deliveries among enrollees ages 18–44 with diabetes or HDP, continuously enrolled for at least 60 days before and after delivery. Main Measures: A primary care visit within 3, 6, and 12 months postpartum. Results: Overall, 53.6%, 76.8%, and 90.3% were linked to primary care by 3, 6, and 12 months, respectively. Although positive, ACO implementation was not associated with statistically significant changes at any interval for either model. At 3 months, model 1 was associated with a 2.44 percentage point [PP] increase (95% CI: −1.7 to 6.6) and model 2 with a 3.73 PP increase (95% CI: −0.5 to 8.0) versus non-ACO enrollees. Conclusions: Massachusetts Medicaid ACO implementation was not associated with significant changes in postpartum primary care linkage. Explicit postpartum performance measures and stronger coordination between maternity and primary care clinicians may be needed to improve transitions to ongoing care.