Comparison of Office-Based Physician Participation in Medicaid Managed Care and Health Insurance Exchange Plans in the Same US Geographic Markets

IMPORTANCE: Several recent policy proposals have sought to expand the role of Medicaid in providing health insurance for low-income Americans, but there is little recent information on how physician participation in Medicaid compares with alternative forms of coverage for low-income Americans. OBJECTIVE: To compare the number of office-based physicians included in Medicaid managed care and health insurance exchange plans that operate in the same geographic markets. DESIGN, SETTING, AND PARTICIPANTS: This cross-sectional study used administrative data from physician network directories and survey data from office-based physicians for Kansas, Nebraska, New York, Tennessee, and Washington. The number of participants totaled 67 057 office-based physicians in the 5 sample states. Data were collected and analyzed from May 2018 to June 2019. EXPOSURES: Physician participation in a Medicaid managed care or health insurance exchange plan network. MAIN OUTCOMES AND MEASURES: The percentage of office-based physicians in a county who indicated during a phone survey that they participated in Medicaid; the percentage of office-based physicians in a county who participated in each Medicaid managed care and health insurance exchange plan network; and the percentage of office-based physicians in a county who participated in at least 1 Medicaid managed care plan or, separately, at least 1 health insurance exchange plan. RESULTS: Of the 67 057 office-based physicians in our sample, 49 983 reported in a telephone survey that they accepted Medicaid. This survey-based measure undercounted the percentage of physicians participating in Medicaid by 5.2% (95% CI, 2.3%-8.1%; P < .001) relative to a measure based on physician network directories. Medicaid managed care physician networks covered a median (interquartile range) of 63.4% (48.0%-81.3%) of office-based physicians compared with health insurance exchange physician networks, which covered 51.0% (31.0%-70.5%). In adjusted analyses, Medicaid managed care plans covered 6.2% (95% CI, 3.2%-9.3%, P < .001) more office-based physicians than health insurance exchange plans operating in the same counties. In the states where the same insurers participated in both markets (New York, Tennessee, Washington), the Medicaid managed care physician networks were 6.5% (95% CI, 3.2%-9.8%, P < .001) larger than the health insurance exchange networks offered by the same insurer. CONCLUSIONS AND RELEVANCE: In this cross-sectional study of physician network data, Medicaid managed care physician networks included more office-based physicians than the physician networks of health insurance exchange plans operating in the same geographic markets. This suggests that Medicaid remains a viable option for expanding coverage in the United States.