Submitted for Publication: May 6, 2013; final revision received September 28, 2013; accepted October 14, 2013.
Published Online: December 12, 2013. doi:10.1001/jamaoto.2013.5988.
Study concept and design: Chen, Purdy.
Acquisition of data: Chen, Vazquez, Courquin.
Analysis and interpretation of data: Chen, Daly, Farwell, Lau.
Drafting of the manuscript: Chen, Vazquez.
Critical revision of the manuscript for important intellectual content: Chen, Daly, Farwell, Courquin, Lau, Purdy.
Statistical analysis: Chen.
Administrative, technical, and material support: Chen, Vazquez, Courquin, Lau, Purdy.
Study supervision: Chen, Vazquez.
Conflict of Interest Disclosures: None reported.