The Centers for Medicare and Medicaid Services (CMS) changed the benchmark methodology for accountable care organizations (ACOs) entering a renewal Medicare Shared Savings Program (MSSP) agreement period in 2017 and thereafter. The 2017 methodology introduced a regional adjustment, where an ACO’s historical expenditures are adjusted upward or downward based on how their costs compare to regional expenditures on a risk-adjusted basis. Because the risk adjustment depends on an ACO’s benchmark period risk scores, accurate and complete diagnosis coding during the benchmark period now has a significant influence on the calculation of the ACO’s benchmarks in future performance years.
CMS uses benchmark year (BY) 3 risk scores for the calculation of the regional adjustment, scores that are based on diagnoses from claims incurred in BY2. MSSP ACOs anticipating renewals in 2020 need to be working this year (2018) to ensure accurate and complete coding. Similarly, 2019 is the critical year for 2021 renewals.
In this paper, Milliman’s Jonah Broulette, Noah Champagne, and Kate Fitch explain how BY3 risk scores affect the benchmark calculation for MSSP renewals, present an overview of the prior and new risk adjustment calculations in MSSP, and illustrate how the change can affect an ACO’s benchmark under various scenarios.