With the Affordable Care Act's (ACA) expansion of Medicaid, approximately 15 million people were able to enroll in the program - many of whom were previously uninsured. However, researchers have long worried that an expansion of insurance coverage would not translate to an equal expansion in access to care. A particular point of concern is the worry that these newly eligible and enrolled individuals would not be able to find enough physicians who participate in Medicaid to treat them. 

Existing research has traditionally relied on physician survey data to study trends in physician acceptance of Medicaid and the factors associated with participation in the Medicaid program. For example, under contract with the Medicaid and CHIP Payment and Access Commission (MACPAC), SHADAC researchers used data from the National Electronic Health Records Survey (NEHRS) to create state-level estimates of physician participation in Medicaid before and after expansion and to study the physician- and practice-level characteristics associated with participation.

However, a new study led by Dr. Hannah Neprash is the first to provide direct answers about how clinicians responded to the Medicaid expansion. In their paper, "The effect of Medicaid expansion on Medicaid participation, payer mix, and labor supply in primary care” published in the December 2021 issue of the Journal of Health Economics, Dr. Neprash and her co-authors use all-payer claims and practice management data from 2012 through 2017 to examine how clinicians changed their labor supply and payer mix in response to Medicaid expansion.

This brief summarizes key findings from this study, including the effect of expansion on the number of Medicaid appointments and number of Medicaid patients seen by primary care clinicians (i.e., Medicaid participation), the total number of appointments provided (i.e., their labor supply) and the share of those appointments paid for by Medicaid versus private coverage or other payers (i.e., payer mix). The study also compares the relative change in participation in states subject to the Medicaid expansion compared to the change in states not subject to the expansion, estimating a causal effect of expansion on clinician participation in Medicaid.

Click on the image to the upper right to access and download a PDF of the full brief.

Related Resources

Physician Acceptance of New Medicaid Patients: Findings from the National Electronic Health Records Survey (MACPAC Fact Sheet)

Explore Physician Acceptance of New Medicaid Patients through Two New Measures on SHADAC’s State Health Compare and in a New MACPAC Factsheet (SHADAC Blog)

Physicians who accept new Medicaid patients (State Health Compare Data Measure)