Received: 11 January 2019
Accepted: 29 May 2019
First Online: 7 June 2019
Ethics approval and consent to participate
: Ethical approval was obtained from the Institutional Review Board of Seoul National University Hospital (IRB Number 1804–169-942).
: Consent to participate was waived due to the retrospective nature of the study.
: The authors declare that they have no competing interests.