Received: 28 January 2021
Accepted: 21 April 2021
First Online: 27 April 2021
: The Institutional Review Board of Ulsan University Hospital approved the study protocol (2020-01-018) and waived the need for informed consent for this study given the non-requirement of consent in retrospective analyses covered by regulations in Korea. This study was performed in accordance with the ethical standards of the institutional research and the Declaration of Helsinki.
: Not applicable.
: The authors declare that they have no competing interests.