Factors affecting Accountable Care Organizations' decisions to remain in or exit the Medicare Shared Savings Program following Pathways to Success.

The Medicare Shared Savings Program (MSSP) is an alternative payment model launched in 2012, creating Accountable Care Organizations (ACOs) to improve quality and lower costs for Traditional Medicare patients. Most MSSP participants were expected to shift from bearing no financial risk to a 2-sided risk model (ie, bonus if spending reduced below historical benchmarks, penalty if not), yet fewer than 20% did. Therefore, in 2019, the Centers for Medicare and Medicaid Services launched the Pathways to Success program, which required shifting to a 2-sided model within 12 months. For the first time, more ACOs exited than entered the MSSP. To understand these participation decisions, we conducted qualitative interviews with ACO leaders. Pathways caused ACOs to reassess their potential shared savings vs losses, particularly in light of benchmarking methodology changes; reconsider perceived nonrevenue benefits; and reassess participation in the MSSP vs other programs. As ACOs, particularly those assuming downside risk, have contained costs and enhanced care quality, policymakers should strive to improve MSSP enrollment rates in downside-risk models through strategies that allow ACOs to achieve shared savings and deliver accountable care.