Received: 1 October 2020
Accepted: 10 January 2021
First Online: 15 January 2021
Ethics approval and consent to participate
: This population-based observational study was conducted and reported according to the Reporting of Observational Studies in Epidemiology guidelines. The study protocol was approved by the Institutional Review Board (X-2004-604-905) and the Health Insurance Review and Assessment Service (NHIS-2020-1-291). The need for informed consent was waived because the data analyses were performed retrospectively using anonymized data derived from the South Korean NHIS database.
: Not applicable.
: The authors declare that they have no competing interests.