Funding for this research was provided by:
National Research Foundation of Korea (NRF-2017R1D1A1B03031642)
Received: 1 September 2019
Accepted: 14 January 2020
First Online: 30 January 2020
Ethics approval and consent to participate
: The institutional review board of Seoul National University Hospital approved the study design (no. H-1808-011-963), which was conducted in accordance with the principles of the Declaration of Helsinki. This retrospective study was qualified for a waiver of consent.
: Not applicable.
: The authors declare that they have no competing interests.