Submitted for Publication: April 29, 2014; final revision received July 7, 2014; accepted July 12, 2014.
Published Online: August 28, 2014. doi:10.1001/jamaoto.2014.1657.
Study concept and design: Robertson, Yule, Wynne, Russell.
Acquisition, analysis, or interpretation of data: Smillie, Robertson, Yule, Russell.
Drafting of the manuscript: Smillie, Robertson, Yule.
Critical revision of the manuscript for important intellectual content: Smillie, Wynne, Russell.
Statistical analysis: Smillie, Robertson, Yule.
Administrative, technical, or material support: Smillie, Robertson, Yule, Wynne.
Study supervision: Wynne, Russell.
Conflict of Interest Disclosures: None reported.