Author Contributions: As principal investigator, Dr Stukel 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: Stukel, Fisher, Wennberg.
Acquisition of data: Fisher.
Analysis and interpretation of data: Stukel, Fisher, Wennberg, Alter, Gottlieb, Vermeulen.
Drafting of the manuscript: Stukel.
Critical revision of the manuscript for important intellectual content: Stukel, Fisher, Wennberg, Alter, Gottlieb, Vermeulen.
Statistical analysis: Stukel, Gottlieb, Vermeulen.
Obtained funding: Fisher.
Administrative, technical, or material support: Wennberg.
Study supervision: Stukel.
Financial Disclosures: None reported.
Funding/Support: This study was supported by grants from the Robert Wood Johnson Foundation, the US National Institute on Aging (1PO1-AG19783-01), and Canadian Institutes of Health Research (CTP79847) Team Grant in Cardiovascular Outcomes Research.
Role of the Sponsors: The funding agencies did not participate in the design and conduct of the study, in the collection, analysis, and interpretation of the data, or in the preparation, review, or approval of the manuscript.
Disclaimer: The content of this article reflects the views of the authors alone and does not necessarily reflect the opinions of the Centers for Medicare & Medicaid Services or the funding agencies.
Acknowledgment: We thank Douglas O. Staiger, PhD, Department of Economics, Dartmouth College, Hanover, NH, for his insightful contributions, Kelvin Lam, MSc, Institute for Clinical Evaluative Sciences, Toronto, Ontario, for his assistance with data analysis, and Nancy MacCallum, MLIS, Institute for Clinical Evaluative Sciences, Toronto, Ontario, for her assistance with manuscript preparation. None received compensation for their work.