Author Contributions: Dr Reed 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: Reed, Kern, Wright.
Acquisition of data: Reed.
Analysis and interpretation of data; critical revision of the manuscript for important intellectual content: Reed, Kern, Levine, Wright.
Drafting of the manuscript: Reed, Wright.
Statistical analysis: Reed, Levine, Wright.
Obtained funding; administrative, technical, or material support: Kern.
Study supervision: Kern, Wright.
Financial Disclosures: None reported.
Funding/Support: Dr Reed is a Mayo Foundation Scholar and a Ruth L. Kirschstein National Research Service Award trainee, grant 5 T32 HP10025. Dr Wright is an Arnold P. Gold Foundation Associate Professor of Medicine.
Role of the Sponsors: The funding organizations had no role in the design and conduct of the study; the collection, management, analysis, and interpretation of the data; or the preparation, review, or approval of the manuscript.
Acknowledgment: The statistical analysis was performed by the authors of this study and reviewed by Ken Kolodner, PhD, a private statistical consultant. We thank Dr Kolodner for his statistical expertise and Cheri Smith, MLS, Harrison Medical Library, Johns Hopkins Bayview Medical Center, Baltimore, Md, for her assistance with the literature review. Dr Kolodner received compensation for providing statistical consultation.