Published Online: May 5, 2014. doi:10.1001/jamapediatrics.2014.345.
Study concept and design: All authors.
Acquisition, analysis, or interpretation of data: All authors.
Drafting of the manuscript: Bennett.
Critical revision of the manuscript for important intellectual content: All authors.
Statistical analysis: Bennett, Thompson, Carroll, Downs.
Obtained funding: Downs.
Administrative, technical, or material support: Downs.
Study supervision: Downs.
Conflict of Interest Disclosures: None reported.