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. Author manuscript; available in PMC: 2015 Apr 30.
Published in final edited form as: N Engl J Med. 2014 Oct 30;371(18):1715–1724. doi: 10.1056/NEJMsa1406552

Figure 1. Survey and Study Periods Relative to the Start of Accountable Care Organization (ACO) Contracts in 2012.

Figure 1

The Consumer Assessment of Healthcare Providers and Systems (CAHPS) survey of fee-for-service Medicare beneficiaries is administered annually from March through May; in the period from 2010 through 2013, a total of 82.2% of the respondents were surveyed by the end of April. The 2013 survey was administered 8 to 14 months after Medicare Shared Savings Program (MSSP) ACO contracts started in April or July of 2012 (the first and second rounds, respectively) and 14 to 17 months after Pioneer ACO contracts started in January 2012. The 2012 survey was administered an average of 3 months after the start of Pioneer ACO contracts, but the reference period included up to 4 months before the start dates because the CAHPS questions on patients’ experiences refer to the preceding 6 months of care. We did not expect substantial changes in patients’ experiences within 3 months after exposure to ACO contract incentives, and the 2012 survey reference period overlapped minimally with the MSSP ACO contract periods. Accordingly, we defined the preintervention period to include survey data from the period from 2010 through 2012 and the postintervention period to include 2013 survey data.