Accountable care organizations (ACOs), Medicare's flagship reform to slow cost growth, were envisioned as local, clinically integrated networks of clinicians and hospitals caring for shared patients. Increasingly, third-party firms known as conveners have recruited clinicians into Medicare Shared Savings Program (MSSP) ACOs. Conveners provide capital and analytic infrastructure, but they may also strategically aggregate low-cost clinicians across large, geographically dispersed networks. Using national MSSP data from the period 2012-21, we found that the share of beneficiaries in convener-led ACOs grew from 11 percent to 23 percent. The share of beneficiaries in dispersed ACOs increased over time, rising sharply from 13 percent to 42 percent among convener ACOs. Dispersed convener ACOs earned the highest shared-savings payments (171 per beneficiary per year), whereas local convener ACOs earned the lowest (95), without evidence of higher-quality performance. These findings suggest that third-party conveners are reshaping the structure of the MSSP. Policy makers should strengthen the disclosure of convener relationships and consider network definition rules to promote coordinated care in the MSSP.
Markovitz et al. (Mon,) studied this question.