Performance Differences in Year 1 of Pioneer Accountable Care Organizations

The New England Journal of Medicine
April 2015
McWilliams, J.M., Chernew, M. E., Landon, B.E., and Schwartz, A.L.

In 2012, a total of 32 organizations entered the Pioneer accountable care organization (ACO) program, in which providers can share savings with Medicare if spending falls below a financial benchmark. Performance differences associated with characteristics of Pioneer ACOs have not been well described. Drawing on HCFO-funded work, this article compares per-beneficiary Medicare spending and performance on several quality measures between Pioneer ACOs and local nonparticipating providers before versus after the start of Pioneer ACO contracts in 2012. Using a difference-in-differences analysis the researchers compared savings estimated by this approach between policy-relevant subgroups of ACOs. Their study results show that year 1 of the Pioneer ACO program was associated with modest reductions in Medicare spending. Savings were greater for ACOs with higher baseline spending than for those with lower baseline spending and were unrelated to withdrawal from the program.

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