Funding for this research was provided by:
National Research Foundation of Korea (NRF-2018R1A2B6007094, MSIP No. 2014R1A5A2010008)
Received: 6 April 2020
Accepted: 12 July 2020
First Online: 18 July 2020
Ethics approval and consent to participate
: The protocol for data collection was approved by the Institutional Review Board (IRB) of each hospital (Ajou University hospital’s IRB: AJIRB-MED-OBS-15-483, Kyungpook National University hospital’s IRB: 2016–01-020, Keimyung University Dongsan hospital’s IRB: 2016–01–038-10). Our study was implemented in accordance with the ethical standards of the 1964 Declaration of Helsinki and its later amendments. The need for written informed consent was waived because of the retrospective nature of this study.
: Not applicable.
: The authors declare that they have no competing interests.