Funding for this research was provided by:
Ewha Womans University (201711-5)
Article History
Received: 22 February 2020
Accepted: 17 May 2020
First Online: 27 May 2020
Ethics approval and consent to participate
: The study protocol was approved by the Institutional Review Board of Ewha (IRB no. EUMC 2020–01-010). Our IRB waived the requirement for informed consent because of the retrospective nature of this national cohort and there was no risk of the exposure of personal information of the participants.
: Not applicable.
: The authors declare that they have no competing interests.