Text and Data Mining valid from 2018-10-26
Received: 2 May 2018
Accepted: 15 October 2018
First Online: 26 October 2018
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of Asan Medical Center, and informed consent was waived because of the retrospective nature of the study. The datasets used and/or analyzed during the current study are available from the corresponding author on reasonable request.
: Not applicable.
: The authors declare that they have no competing interests.
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