Received: 12 September 2018
Accepted: 22 May 2019
First Online: 31 May 2019
Ethics approval and consent to participate
: The retrospective study was performed in accordance with the Declaration of Helsinki and approved by the institutional review boards of Seoul National University Hospital (No: H-1805-055-944) and Samsung Medical Center (No: 2018–09-049). The requirement for written informed consent from patients was waived by the institutional review boards of both centers because clinical data were analyzed anonymously in this study.
: Not applicable
: The authors declare that they have no competing interests.