Text and Data Mining valid from 2020-03-04
Received: 10 November 2019
Accepted: 27 February 2020
First Online: 4 March 2020
Ethics approval and consent to participate
: The need for an approval was waived by the ‘Institutional Review Board of Severance Hospital at Yonsei University College of Medicine’ as the study was retrospective and individual patients were not identifiable.
: Not applicable.
: The authors declare that they have no conflicts of interest.