Funding for this research was provided by:
Hyun Jin Kim Research Grant (KUMCRG05141)
Received: 2 February 2020
Accepted: 22 June 2020
First Online: 2 July 2020
Ethics approval and consent to participate
: This retrospective study was approved by the Ethics Committee of Korea University Anam Hospital. Informed consent for the study was waived.
: Not applicable.
: The authors declare that they have no competing interests.