Corresponding Author: J. Michael McWilliams, MD, PhD, Department of Health Care Policy, Harvard Medical School, 180 Longwood Ave, Boston, MA 02115 (mcwilliams@hcp.med.harvard.edu).

Published online: September 9, 2016. doi:10.1001/jama.2016.12049

Conflict of Interest Disclosures: Dr McWilliams has completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest and he reports serving as a consultant to Abt Associates in an evaluation of the ACO Investment Model and as an expert witness to the Federal Trade Commission.

Funding/Support: This work was supported by grant P01 AG032952 from the National Institute on Aging of the National Institutes of Health (NIH).

Role of the Funder/Sponsor: The funder played no role in the design or conduct of the study; collection, management, analysis, or interpretation of the data; preparation, review, or approval of the manuscript; or decision to submit the manuscript for publication.

Additional Contributions: The author thanks Pasha Hamed, MA, for statistical programming support and Jesse B. Dalton, MA (both from Department of Health Care Policy at Harvard Medical School), for research assistance. They were supported by the funding source and received no additional compensation.

Disclaimer: The content is solely the responsibility of the author and does not necessarily represent the official views of the NIH.