Research in Progress (RIP): "Evaluating Accountable Care Organizations"



Michael Chernew, Harvard Medical School

Date and Time

February 19, 2015 4:00 PM - 5:30 PM

FSI Contact

Nicole Feldman

All research in progress seminars are off-the-record. Any information about methodology and/or results are embargoed until publication.



Background: As part of efforts to move away from FFS payment, Medicare established the Accountable Care Organization (ACO) initiative.  ACOs are provider based organizations that can share savings with Medicare if spending falls below a financial benchmark and are rewarded if they meet quality metrics.  There are now over 400 ACOs.

Methods: In a difference-in-differences analysis of Medicare, we assess the impact of ACOs on spending, patient satisfaction, and quality.  

Results: Adjusted Medicare spending and spending trends were similar in the ACO and control groups during the pre-contract period.  In 2012, total adjusted per-beneficiary spending differentially changed in the Pioneer ACO group (−$29.2/quarter; P=0.01), consistent with a 1.2% savings.  Savings were significantly greater for ACOs with baseline spending above the local average (P=0.048) and those serving high-spending areas (P=0.04).  Savings were unrelated to financial integration between hospitals and physician groups and significant among ACOs that exited the program. Quality in the Pioneers either improved or was similar.  Patient experiences (in Pioneers and Shared Savings ACOs) were either statistically similar or better that traditional FFS, with the improvements in areas that ACOs can more readily impact and for patients they are likely to target.

Conclusion:  Early results from the ACO program suggest ACOs can achieve savings without lowering quality or patient satisfaction.