Nearly one-third of physicians enrolled in Medicaid do not treat any patients covered by the program, according to a new study led by Oregon Health & Science University (OHSU). The research, published in Health Affairs, examines the disconnect between Medicaid provider enrollment data and actual patient care. Medicaid currently covers close to 80 million Americans.
The study found that while many physicians are listed as participating in Medicaid, only a portion actively see Medicaid patients. Another third of providers who do participate have heavy caseloads—more than 150 Medicaid patients per year—raising concerns about potential overburdening. This suggests that the availability of care for Medicaid enrollees is more limited than enrollment figures indicate.
Lead author Jane Zhu, M.D., associate professor at OHSU School of Medicine, stated: "Low physician participation in Medicaid is a commonly cited reason for access gaps and unmet need in Medicaid. If patients aren't able to access the care they need, they may delay or forego care altogether, which is not only bad for patient outcomes, but also bad for the health system overall."
Zhu noted that delayed or missed care can result in sicker patients with more complex conditions and higher costs over time.
The research analyzed administrative claims and provider enrollment across five specialties: primary care, psychiatry, cardiology, dermatology and ophthalmology. Actual participation lagged behind enrollment numbers across all fields studied. The gap was most pronounced among psychiatrists; more than 40% were enrolled but did not see any Medicaid patients during the year.
Researchers described these non-participating physicians as "ghost" providers—a term reflecting previous findings from an earlier Health Affairs study on Oregon's Medicaid program.
"Patients may call providers who say they are enrolled in Medicaid, but those calls go nowhere," Zhu said. "People give up because those providers aren't actually available to see them."
Zhu explained some providers may be listed due to contractual obligations or full schedules with commercially insured patients rather than an intent to serve those on Medicaid.
She emphasized that policymakers should focus on patient experiences when assessing access to care: "Maintaining access to care is a really big problem with increasing demand for services and workforce shortages. A clearer picture would help policymakers better spend public dollars on levers that meaningfully impact provider participation."
The study used Transformed Medicaid Statistical Information System Analytic Files covering data from 2019 through 2021—the most recent available at the time of analysis.
Co-authors include Kirbee Johnston, M.P.H., Kyle Hart, M.S., John McConnell, Ph.D., all from OHSU Center for Health Systems Effectiveness; and Daniel Polsky from Johns Hopkins University.
