Author Contributions: Dr Landon had full access to all of the data in the study and takes responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Landon, Keating, Barnett, Onnela, O’Malley, Christakis.
Acquisition of data: Landon, Christakis.
Analysis and interpretation of data: Landon, Keating, Barnett, Onnela, Paul, O’Malley, Keegan, Christakis.
Drafting of the manuscript: Landon, Onnela, O’Malley, Christakis.
Critical revision of the manuscript for important intellectual content: Keating, Barnett, Paul, O’Malley, Keegan, Christakis.
Statistical analysis: Landon, Barnett, Onnela, Paul, O’Malley.
Obtained funding: Landon, O’Malley, Keegan, Christakis.
Administrative, technical, or material support: Keegan, Christakis.
Study supervision: O’Malley, Christakis.
Conflict of Interest Disclosures: The authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Drs Landon and Christakis have an equity stake in a company, Activate Networks, which is licensed by Harvard University to apply some of the ideas embodied in this article. Dr Landon reported serving on the scientific advisory board for Activate Networks; serving on the medical advisory board for Navigenics; and serving as a consultant to the Massachusetts Medical Society, United Biosource, and Research Triangle Institute. Dr Barnett reported serving as a consultant to Ginger.io and having a patent application pending. Dr Onnella reported serving as consultant to MedNetworks. Dr O’Malley reported serving as a consultant to Daller Shaller Consulting and receiving reimbursement for travel expenses from the National Institutes of Health. Dr Christakis reported serving on the scientific advisory board for and as a consultant to Activate Networks. No other authors reported disclosures.
Funding/Support: This work was supported by grant P-01 AG-031093 from the National Institute on Aging. Dr Barnett was supported by a Doris Duke Charitable Foundation Clinical Research Fellowship and a Harvard Medical School Research Fellowship.
Role of the Sponsor: The funding organizations had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; and preparation, review, or approval of the manuscript.
Online-Only Material: The interactive that goes with Figure 2A is available.
Additional Contributions: We gratefully acknowledge Alan Zaslavsky, PhD, for statistical advice, Rick McKellar, BA, for research assistance, and Laurie Meneades, BS, for expert data management and programming (all 3 are with the Department of Health Care Policy, Harvard Medical School). The persons listed in this section were compensated for their contributions as part of their salaries at Harvard Medical School.