Funding for this research was provided by:
Korea Centers for Disease Control and Prevention (2018P330400)
Received: 16 April 2020
Accepted: 23 November 2020
First Online: 1 December 2020
Ethics approval and consent to participate
: The Seoul National University Institutional Review Board (IRB number: E-1806-076-951) approved this study. The requirement for informed consent was waived as the NHIS database was anonymized according to strict confidentiality guidelines prior to distribution.
: Not applicable.
: The authors declare that they have no competing interests.