Accountable Care Organizations (ACOs) are a payment and delivery model designed to incentivize the provision of high-quality care at lower cost. Evidence of reduced spending in Medicare ACOs compared to traditional payment models has prompted states to experiment with the use of ACOs in their Medicaid programs. Preliminary reports from Medicaid ACOs have shown a reduction in emergency department use, rehospitalizations, and readmissions. Medicaid ACOs are increasingly common, with active programs in 12 states.
Distinct in structure from Medicare ACOs where Medicare enrollees with traditional Medicare assigned to ACOs can visit any primary care or specialist clinician accepting Medicare, Medicaid ACO enrollees are generally restricted to primary care and specialist clinicians within the ACO and/or associated managed care plan. Given that Medicaid enrollees can face access issues related to a lack of participating clinicians, understanding the clinicians included for members of Medicaid ACOs is an important policy question. Federal government standards require states to have quantitative network adequacy standards (e.g., time and distance standards), but these differ substantially in measurement and enforcement by state. Thus, even provider networks for Medicaid managed care plans and Medicaid ACOs that meet state government regulations may vary substantially and impact patient access.
As of 2020, over half of physicians nationally are participating in at least one ACO of any type with just over a quarter of physicians participating in a Medicaid ACO. Physicians in hospital-owned practices, multispecialty groups, and in practices with at least some primary care physicians are more likely to participate in Medicaid ACOs. Previous research on novel Medicaid ACO models has identified barriers to provider participation, including provider perception of potential penalization for their performance as well as lack of incentives for individual clinicians to change their delivery model.
Most research on clinician participation in Medicaid ACOs has focused on primary care clinicians, but the inclusion of maternity care providers–both clinicians and hospitals with obstetric departments–is also critical for a Medicaid population that is disproportionately likely to use these services. Due to higher income eligibility thresholds during pregnancy, over 40% of births nationally are covered by Medicaid. Recent work identifying influential characteristics in women’s choice of where to receive obstetric/gynecologic or reproductive care ranked insurance network as the second most important factor, behind quality. Another study found 96% of mothers cited accepting their health insurance plan as a major factor when choosing a prenatal care provider and birth hospital. Understanding inclusion of providers and overlap among Medicaid ACOs is particularly important given ongoing transitions in insurance plans, including among those insured by Medicaid, during the perinatal period. Obstetrician-gynecologists (OB/GYNs) are uniquely placed as physicians because they provide preventive services and act as primary care providers for some patients and 25% of women consider their OB/GYN to be their primary care provider; however, they do not always provide the full range of preventive services offered by family physicians and internists, and have not been used to build primary care-focused ACOs. However, OB/GYNs differ from other specialists in that some states and state Medicaid programs require health plans to allow patients to see OB/GYNs without a referral, even if they are not the patient’s designated PCP.
As alternative payment models, including ACOs, become more common in all insurance types, understanding the differences in provider network breadth in Medicaid ACOs is increasingly important to ensure patient access to care. In Medicaid ACOs, adequate networks of OB/GYN providers are essential to ensuring high quality care for women. In this study, we quantify maternity care provider inclusion in Massachusetts Medicaid ACOs, implemented starting in March 2018, and analyze differences in provider inclusion by specific Medicaid ACO type.