Received: 28 September 2020
Accepted: 23 December 2020
First Online: 11 January 2021
Ethics approval and consent to participate
: Informed consent was waived because of the retrospective study design, and the study was approved by the institutional review boards of all participating institutes. (Ewha Womans University: EUMC 2020–07–010-002, Korean University: 2020GR0347, Soonchunhyang University: SCHBC2020–08-027, Hallym University: 2020–07-014, and Inha University: 2020–07-008).
: Not applicable.
: The authors declare that they have no competing interests.