On November 1, the sixth year of open enrollment on the ACA Marketplace will start. While the basic rules that govern the Marketplace and the sliding-scale subsidies remain intact, gains in enrollment are unlikely given the end of penalties for the individual mandate, the emergence of association health plans, and new rules related to “short-term limited duration.”

While the market in which Marketplace plans are sold remains in flux, less attention is paid to the characteristics of the plans themselves. In our recent study in Health Affairs, we compare the scope of primary care physician participation in the Marketplace with employer-sponsored insurance (ESI) and Medicaid. It has been shown that physicians are less likely to accept new Medicaid patients compared to privately insured patients, but outside of some evidence of restricted provider choice, little is known about physician participation for plans purchased in the Marketplace.

For Marketplace plans, ESI, and Medicaid we assessed the in-network rate, which measures the share of physicians that accepted at least one insurance plan in the different insurance market segments, and the appointment availability rate, which measures the rate of in-network offices that successfully scheduled new patient appointments with simulated patients.

Across our ten-state sample, we found a clear pattern of access across insurance types: in-network rates and appointment availability rates for Marketplace plans fell between employer-sponsored insurance and Medicaid. In 2016, the in-network rate for Marketplace and Medicaid plans were 91% and 75% of the size of employer-sponsored insurance networks. Likewise, the appointment availability rate was 85% for employer-sponsored insurance, 73% for the Marketplace, and 66% for Medicaid.

The differences in provider choice for plan beneficiaries in each of these insurance market segments reflect inherent trade-offs in increasing coverage. The implications of these findings for policymakers depend largely on the weight of competing interests.

• If efficiency is the priority, our results could reflect a functioning market where differences in provider choice result from a different willingness to pay in each insurance market segment. 
• If provider choice is the priority, our findings suggest that offering beneficiaries in one market segment the option of a broader market segment may be worth the cost.
• If health equity among those with different insurance types is the priority, however, investing to close these gaps should be considered.

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The study, Scope Of Primary Care Physicians’ Participation In The Health Insurance Marketplaces, was published in Health Affairs in August 2018. Authors include Daniel Polsky, Molly K. Candon, Paula Chatterjee, and Xinwei Chen.