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Evaluation of the Accountable Care Organization Investment Model: AIM Implementation and Impacts over Two Performance Years

Abt Global, L&M Policy Research, Insight Policy Research


September 10, 2019

This report for the Centers for Medicare & Medicaid Services (CMS) presents evaluative findings on Accountable Care Organizations (ACOs) participating in the ACO Investment Model (AIM) under the Shared Savings Program. AIM ACOs receive up-front and ongoing payments from CMS, which are paid back through savings generated by the ACO relative to a benchmark spending level.  These AIM payments help the ACOs fund infrastructure investments or staffing, with the goals of promoting development of ACOs in regions with few ACOs and encouraging existing ACOs to maintain participation and transition to two-sided financial risk.

This report finds that during the first two performance years, AIM ACOs were successful in decreasing total Medicare spending. Importantly, these reductions in spending did not result in lower quality health care.  Additionally, most AIM ACOs reported they would not have participated in the program without AIM funding.

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