'Ghost' Physicians: More Than One-Quarter Of Physicians Enrolled In Medicaid Delivered No Care To Beneficiaries In 2021.

Concerns about low physician participation in Medicaid have long motivated policy reforms, but the extent to which enrolled physicians actually care for Medicaid patients remains unclear. To assess patterns of Medicaid participation among physicians, we linked physician enrollment files to Medicaid administrative claims from the period 2019-21, focusing on five physician specialties: cardiology, dermatology, ophthalmology, primary care, and psychiatry. We examined the proportion of Medicaid-enrolled physicians with any claims activity and the volume of unique Medicaid patients and encounters per physician. We found that although 68-89 percent of physicians were enrolled in Medicaid, nearly 28 percent delivered no care to Medicaid beneficiaries in 2021. Participation in Medicaid varied widely by specialty: More than 40 percent of psychiatrists were "ghost" physicians who saw no Medicaid enrollees in a given year, whereas primary care physicians were most likely to be high-volume "core" participants. Although most physicians maintained stable participation over time, approximately one-fifth of ghost providers and one-third of "peripheral" providers (those seeing 1-10 Medicaid enrollees per year) transitioned to a higher-engagement group between 2020 and 2021. Taken together, our findings demonstrate that given relatively limited and variable Medicaid participation, targeted policy efforts-particularly in specialties such as psychiatry-may help strengthen physician engagement and reduce access gaps.