Received: 14 March 2020
Accepted: 3 June 2020
First Online: 10 June 2020
Ethics approval and consent to participate
: This study was conducted in accordance with the Declaration of Helsinki. This study was approved by the institutional review board of Seoul National University Bundang Hospital (IRB approval No. B-1707/408–106). Written consent was waived by the IRB due to the retrospective nature of the study. All the data were fully anonymized before access by the researchers.
: Not applicable.
: The authors declare that they have no competing interests.