Primary Care Provider Medicaid Participation Across the United States, 2016.

To understand primary care provider participation in Medicaid programs across states and provider specialties and professions. We examined the 2016 Medicaid claims data across 45 states and territories from the Transformed Medicaid Statistical Information System (T-MSIS). Of the 616,182 primary care providers we identified, 111,152 (18.0%) saw no Medicaid patients, 88,723 (14.4%) providers saw one to 10 Medicaid patients, 163,806 (26.6%) saw 11 to 100 Medicaid patients, and 252,501 (41.0%) saw more than 100 Medicaid patients in 2016. The proportion of providers who saw more than 100 Medicaid patients ranged from 22.9% in Virginia to 56.1% in New Mexico. Medicaid participation also differed by specialty, from 78.4% among pediatricians to 61.2% among nurse practitioners. This study lays the foundations for using T-MSIS data to identify communities at the highest risk for access barriers and support targeted policy responses.