Primary Care Physician Networks In Medicare Advantage.

Medicare Advantage (MA) plans often establish restrictive networks of covered providers. Some policy makers have raised concerns that networks may have become excessively restrictive over time, potentially interfering with patients' access to providers. Because of data limitations, little is known about the breadth of MA networks. Taking a novel approach, we used Medicare Part D claims data for 2011-15 to examine how primary care physician networks have changed over time and what demographic and plan characteristics are associated with varying levels of network breadth. Our findings indicate that the share of MA plans with broad networks increased from 80.1 percent in 2011 to 82.5 percent in 2015. Enrollment in broad-network plans grew from 54.1 percent to 64.9 percent over the same period. In an adjusted analysis, we detected no significant time trend. In addition, narrow networks were associated with urbanicity, higher income, higher physician density, and more competition among plans. Health maintenance organizations had narrower networks than did point-of-service plans, whose networks were narrower than those of preferred provider organizations.