Received: 26 February 2021
Accepted: 27 July 2021
First Online: 12 August 2021
: This study was approved by the institutional review board (IRB) of Seoul National University Bundang Hospital (IRB number: B-2003-601-103), and all methods in this study were carried out in accordance with relevant guidelines and regulations. The need of obtaining informed consent was waived by the institutional review board (IRB) of Seoul National University Bundang Hospital because of the retrospective nature of this study.
: Not applicable.
: The authors declare that they have no competing interests.