Author Contributions: Drs Volpp and Silber had full access to all of the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis.
Study concept and design: Volpp, Rosen, Rosenbaum, Romano, Bellini, Silber.
Acquisition of data: Volpp, Even-Shoshan, Behringer, Silber.
Analysis and interpretation of data: Volpp, Rosen, Rosenbaum, Romano, Wang, Bellini, Silber.
Drafting of the manuscript: Volpp, Rosenbaum, Silber.
Critical revision of the manuscript for important intellectual content: Volpp, Rosen, Rosenbaum, Romano, Even-Shoshan, Wang, Bellini, Behringer, Silber.
Statistical analysis: Volpp, Rosenbaum, Romano, Wang, Silber.
Obtained funding: Volpp, Rosen, Rosenbaum, Even-Shoshan, Silber.
Administrative, technical, or material support: Volpp, Even-Shoshan, Bellini, Behringer, Silber.
Study supervision: Volpp, Rosen, Rosenbaum, Silber.
Financial Disclosures: None reported.
Funding/Support: This work was supported primarily by grant R01 HL082637 from the National Heart, Lung, and Blood Institute. Additional support was received by grant IIR 04.202.1 from the US Veterans Affairs Health Services Research and Development Service and grant SES-0646002 from the National Science Foundation.
Role of the Sponsors: The sponsors had no role in the design and conduct of the study, in the collection, management, analysis, and interpretation of the data, or in the preparation, review, or approval of the manuscript.
Additional Contributions: Hong Zhou, MS, Children's Hospital of Philadelphia, provided assistance in preparing the Medicare data for analysis and Michael Halenar, BA, University of Pennsylvania, provided assistance as a research assistant. Ms Zhou and Mr Halenar received financial compensation for their contributions.