Funding for this research was provided by:
Samsung Medical Center (OTA1802901)
Received: 5 August 2019
Accepted: 11 September 2019
First Online: 26 September 2019
Ethics approval and consent to participate
: The Institutional Review Board of Samsung Medical Center approved this study and waived the requirement for informed consent given its observational nature.
: Not applicable.
: The authors declare that they have no competing interests.