Received: 6 November 2019
Accepted: 21 May 2020
First Online: 9 June 2020
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board (IRB) of Gangnam Severance Hospital (IRB No: 3-2019-0072). Owing to the retrospective nature of this study, the requirement for informed consent was waived.
: Not applicable.