Submitted for Publication: November 5, 2013; final revision received January 22, 2014; accepted February 5, 2014.
Published Online: March 27, 2014. doi:10.1001/jamaoto.2014.243.
Study concept and design: Jeong, Chang, Ahn.
Acquisition, analysis, or interpretation of data: Jeong, S. J. Lee, W. Y. Lee.
Drafting of the manuscript: Jeong.
Critical revision of the manuscript for important intellectual content: S. J. Lee, W. Y. Lee, Chang, Ahn.
Statistical analysis: Jeong, S. J. Lee.
Administrative, technical, or material support: W. Y. Lee, Ahn.
Study supervision: Chang, Ahn.
Conflict of Interest Disclosures: None reported.