Funding for this research was provided by:
Korea Centers for Disease Control and Prevention (2018-NG001-00)
Received: 12 June 2019
Accepted: 7 February 2020
First Online: 21 February 2020
Ethics approval and consent to participate
: All procedures were approved by the Institutional Review Boards (IRB) of Cheil General Hospital (IRB number: CGH-IRB-2013-10) and CHA University Gangnam CHA Hospital IRB (IRB number: 2013–14-KNC13–018), separately. All participants provided written informed consent prior to participation, and it was clearly explained to all participants that they were free to withdraw from any part of the study at any point in time.
: Not applicable.
: The authors declare that they have no conflict of interest.