Funding for this research was provided by:
Korea Health Industry Development Institute (HI18C0599)
Received: 16 September 2020
Accepted: 10 February 2021
First Online: 18 February 2021
Ethics approval and consent to participate
: This study was approved by institutional review board of each participating center. Informed consent was waived because this study was considered as posing minimal risk to the study participants because of its retrospective study design.
: Not applicable.
: The authors declare that they have no competing interests.