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Evaluating ACOs and Rural Healthcare for CMS


  • CMS wanted to evaluate the performance of ACOs participating in the ACO Investment Model.
  • Abt conducted a mixed methods evaluation using Medicare claims and qualitative data.
  • Medicare spending was reduced by $381.5 million over three performance years without any decreases in quality
The Challenge

The Centers for Medicare & Medicaid Services (CMS) developed the ACO Investment Model (AIM) to improve health care delivery in rural and underserved areas. AIM provided up-front payments to ACOs participating in Medicare’s Shared Savings Program (SSP). CMS contracted with Abt and our partners to assess AIM in the following areas: (1) ACO formation, risk taking, and sustainability; (2) participant experiences; and (3) impacts of beneficiaries’ health care.

The Approach

We analyzed Medicare Fee-For-Service claims data for beneficiaries attributed to AIM ACOs over the three-year performance period; these AIM ACOs were located in more rural areas with greater disadvantage and less access to care. We also conducted telephone interviews with AIM ACO, practitioners from selected ACOs, and management company representatives. We administered surveys with ACO leadership. Our results were provided to CMS through a series of semi-annual and annual reports.

The Results
  • In 2018, there were 45 AIM ACOs with 5,422 practitioners and 691 institutional providers with 470,129 beneficiaries.
  • AIM reduced per beneficiary per month Medicare spending by $38.73 in 2018, $36.94 in 2017 and $28.21 in 2016.
  • This translated to $381.5 million over two years after netting CMS payments to ACOs in the form of AIM funds and earned shared savings through the second year.
  • Reductions in Medicare spending were driven by decreases in the number of hospitalizations, emergency department visits, and readmissions, and use of institutional post-acute care.
  • The quality of care and patient experience was maintained.

Related Highlights:

Final Evaluation Report | Appendices | At A Glance