

This article is the latest in the Health Affairs Forefront series, Accountable Care for Population Health, featuring analysis and discussion of how to understand, design, support, and measure patient-centered, cost-efficient care under the umbrella of accountable care. Additional articles will be published throughout 2025. Readers are encouraged to review the Call for Submissionsfor this series. We are grateful to Arnold Ventures for their support of this work.
In late October 2024, the Centers for Medicaid and Medicare Services (CMS) released data for the eleventh year of the Medicare Shared Savings Program (MSSP). This marked the seventh consecutive year that the MSSP has achieved savings for Medicare (based on comparisons to the administrative benchmark) and the largest savings in the program’s history according to CMS. The number of participating accountable care organizations (ACOs) decreased slightly from 2022 due to a confluence of factors, but as fewer beneficiaries enroll in traditional Medicare and alternative programs for ACOs such as the ACO Realizing Equity, Access, and Community Health (ACO REACH) Model, attribution in shared savings programs (SSPs) will be challenging. As always, comparisons against benchmarks, including quality, should be interpreted with caution given that savings are calculated from benchmarks set in advance based on a blend of historical and regional spending, our results are unadjusted, and more ACOs are claiming uncontrollable circumstance adjustments (often a function of natural disasters and other emergencies).