Choi, Seung Jun
Ha, Eun-Ju
Jhang, Won Kyoung
Park, Seong Jong
Article History
Received: 16 May 2017
Accepted: 7 February 2018
First Online: 13 February 2018
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board (IRB) of the Asan Medical Center (Number: 2016–1084). The IRB confirmed that no ethical approval for such retrospective analysis of anonymous data is necessary. The need for informed consent was exempted because of the retrospective nature of the study
: Not applicable.
: The authors declare that they have no competing interests.
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