Potential spillover effects on traditional Medicare when physicians bear Medicare Advantage risk.

Objective: The relationship between Medicare Advantage (MA) risk payment arrangements and outcomes for patients in traditional Medicare (TM) has not been empirically examined. The objective of this study was to determine whether providers with greater exposure to MA risk payments are associated with superior outcomes for their TM patients.

Study design: Retrospective, cross-sectional regression analysis.

Methods: Using 2016-2019 Medicare claims, this analysis of TM beneficiaries compared quality and efficiency when care is provided by physicians with high exposure to MA risk payments vs physicians with lower risk exposure. The exposure was physician group exposure to MA risk payments, and the main outcomes were 26 quality and efficiency measures.

Results: Our overall sample comprised 22,257,955 TM beneficiary-years. After we adjusted for demographic differences and risk scores, receiving care from a physician with high risk exposure was associated with higher quality and efficiency across 22 of 26 measures. Improvements in the 22 measures ranged from 3% to 82%.

Conclusions: Our study is the first to examine the association between providers' exposure to MA risk payments and the outcomes they achieve beyond MA, specifically for their TM patients. We found that quality and efficiency outcomes for TM patients were higher under physician groups with high MA risk exposure. Although our study is not causal in nature, to the extent that such a relationship exists, it suggests that the benefits of MA risk payment arrangements extend beyond MA. Consequently, if more MA lives become subject to risk payment arrangements, the magnitude of potential benefits to the TM program could further increase.