Overlap between Medicare's Voluntary Bundled Payment and Accountable Care Organization Programs.

Accountable care organizations (ACOs) and bundled payments represent prominent value-based payment models, but the magnitude of overlap between the two models has not yet been described. Using Medicare data, we defined overlap based on attribution to Medicare Shared Savings Program (MSSP) ACOs and hospitalization for Bundled Payments for Care Improvement (BPCI) episodes at BPCI participant hospitals. Between 2013 and 2016, overlap as a share of ACO patients increased from 2.7% to 10% across BPCI episodes, while overlap as a share of all bundled payment patients increased from 19% to 27%. Overlap from the perspectives of both ACO and bundled payments varied by specific episode. In the first description of overlap between ACOs and bundled payments, one in every ten MSSP patients received care under BPCI by the end of our study period, whereas more than one in every four patients receiving care under BPCI were also attributed to MSSP. Policymakers should consider strategies to address the clinical and policy implications of increasing payment model overlap.