Sending a letter to Medicare beneficiaries increased voluntary alignment to Accountable Care Organizations

Person sitting in front of PC

Person sitting in front of PC

What was the challenge?

Medicare beneficiaries have the opportunity to identify and align with their main health care providers in Accountable Care Organizations (ACOs). ACOs save money while potentially improving patient health by tying payments to care outcomes - ACOs have resulted in an estimated $1.29 billion in savings since 2012. However, the success of the ACO model requires Medicare beneficiaries to be match to an ACO.

What was the program change?

To address the issue of turnover in ACO patient populations, the Center for Medicare and Medicaid Innovation (CMMI) tested a new method for alignment called voluntary alignment, which asks beneficiaries to identify their main doctor. To support this effort, we designed letter and form variations by which beneficiaries would voluntarily align. Letters varied in length, content, and inclusion of the CMMI logo.

How did the evaluation work?

119,512 beneficiaries were randomly sent variations of the letter. Response rates were tracked for each variation.

What was the impact?

The overall response rate to the letter was 37.2%; from those respondents, the confirmation rate was 94%. There were not substantial differences in response rates across the letter designs. The project indicated the operational feasibility and potential for voluntary alignment of ACO patient populations.





Project Type

Impact evaluation of program change


Health and Human Services



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