Received: 26 January 2020
Accepted: 23 June 2020
First Online: 11 August 2020
Ethics approval and consent to participate
: This retrospective data analysis was approved by the Institutional Review Board of Seoul National University (S-D20200007).
: Consent for publication was obtained from all participants.
: Truc Thi Hoang Nguyen, Mi Young Eo, Hoon Myoung, Myung-Joo Kim, and Soung Min Kim declare that they have no competing interests.