Funding for this research was provided by:
Ministry of Health and Welfare (A112005)
National Research Foundation of Korea (2010-0028631)
Text and Data Mining valid from 2018-05-21
Received: 12 October 2017
Accepted: 27 April 2018
First Online: 21 May 2018
Ethics approval and consent to participate
: This study was approved by the IRB of College of Medicine Seoul National University (No 1201–041-394). Informed consent was waived due to the retrospective nature of this study.
: The authors declare that they have no competing interests.
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