Received: 12 November 2020
Accepted: 14 January 2021
First Online: 27 January 2021
Ethics approval and consent to participate
: This study was approved by the Seoul National University College of Medicine/Seoul National University Hospital Institutional Review Board (No. 2006–026-1130) and was conducted in accordance with the Declaration of Helsinki. The need for written informed consent was waived because of the retrospective design and the use of deidentified patient data.
: Not applicable.
: The authors declare they have no competing interest.