Article History
Received: 8 December 2019
Accepted: 5 May 2020
First Online: 11 May 2020
Ethics approval and consent to participate
: The study was approved by the Asan Medical Center Institutional Review Board (IRB number: 2017–0509). Informed consents were waived by the Asan Medical Center Institutional Review Board due to the nature of retrospective study design.
: The authors declare that they have no competing interests” in this section.