Number of beneficiaries assigned to ACOs in Medicare Shared Savings Program 2012-2023

Between 2012/2013 and 2018, the number of beneficiaries assigned to Accountable Care Organizations (ACOs) participating in the Medicare Shared Savings Program (MSSP) increased steadily from 3.2 million to 10.5 million. The figures have fluctuated since then with a total of 10.9 million beneficiaries assigned to ACOs participating in the MSSP by 2023. ACOs are groups of doctors, hospitals, and other health care providers, who voluntarily collaborating to achieve coordinated enhanced quality of care, reduced costs, and improved health outcomes of a designated patient population. ACOs were introduced as part of the Affordable Care Act to shift the U.S. health system from volume-based care (fee-for-service) to value-based care (alternative payment models). Most ACOs receive payment through Medicare or Medicaid, but an increasing number also contract with commercial (or private) payers.