Published Online: December 9, 2013. doi:10.1001/jamainternmed.2013.12693.
Study concept and design: Boiselle.
Acquisition of data: Boiselle.
Analysis and interpretation of data: All authors.
Drafting of the manuscript: Boiselle, Ravenel.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Boiselle.
Administrative, technical, or material support: Ravenel.
Study supervision: Boiselle.
Conflict of Interest Disclosures: None reported.
Correction: This article was corrected online March 10, 2014, for an error in a unit conversion factor.