Integration of Physician and Hospital Networks in Medicaid and the Affordable Care Act's Health Insurance Marketplaces

Background: Little is known about the size and degree of integration between physician and hospital networks in plans sold in the Affordable Care Act’s (ACA) state insurance marketplaces and in the Medicaid program.

Methods: We used social network analytic methods to investigate the size (participation rate) and connectivity (normalized strength) of hospital and physician networks in 38 state insurance marketplaces and in Medicaid. To do so, we matched a near-census of 368,656 office-based physicians and 3,070 hospitals with provider participation data for Medicaid and 96% of marketplace plans.

Results: Participation in at least one marketplace plan ranged from 66.1% of behavioral health clinicians to 93.9% for cardiologists. Medicaid participation rates ranged from 57.1% for behavioral health and 58.7% for adult primary care physicians to 81.2% for cardiology. Individual plan participation rates were considerably smaller, with less than 50% of hospitals and physician specialists listed in marketplace plan networks, on average; there was further variation in network sizes and plan connectivity both within and across states. Despite lower overall Medicaid participation rates, connectivity was greater between marketplace plans and Medicaid than it was between plans listed by different issuers.

Conclusions: Results from this study can be used to identify and monitor provider networks with an insufficient mix of specialists, or with few connections to other plans and to Medicaid. Our network analytic measures can aid patients, clinicians and regulators in making more informed plan choices that promote both competition amongst insurers and continuity of provider relationships and care.