Received: 11 May 2019
Accepted: 18 November 2019
First Online: 3 December 2019
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of the Seoul National University Hospital (IRB No. H-1607-037-774) and conformed to the tenets of the Declaration of Helsinki. Informed consent was waived due to its retrospective nature.
: Not applicable.
: The authors declare that they have no competing interests.