Submitted for Publication: August 23, 2011; final revision received February 3, 2012; accepted February 11, 2012.
Author Contributions: Drs C.-H. Lee and Jung contributed equally to this article. Drs C.-H. Lee, Jung, Rhee, Yoon, Yun, and Kim had full access to all the data in the study and take responsibility for the integrity of the data and the accuracy of the data analysis. Study concept and design: C.-H. Lee, Rhee, Yoon, Yun, and Kim. Acquisition of data: Jung, W. H. Lee, and Kim. Analysis and interpretation of data: C.-H. Lee, Jung, Rhee, and Kim. Drafting of the manuscript: Jung, W. H. Lee, and Kim. Critical revision of the manuscript for important intellectual content: C.-H. Lee, Rhee, Yoon, Yun, and Kim. Statistical analysis: Jung, Rhee, and Kim. Administrative, technical, and material support: Jung and W. H. Lee. Study supervision: C.-H. Lee, Rhee, Yoon, Yun, and Kim.
Financial Disclosure: None reported.