Text and Data Mining valid from 2020-04-03
Received: 1 October 2019
Accepted: 11 March 2020
First Online: 3 April 2020
Ethics approval and consent to participate
: The study protocol was approved by the ethics committee of Seoul National University (IRB number: E-1803-045-928). Individual written informed consent was obtained for the NHIS-NSC from all participants.
: Not applicable.
: The authors declare that they have no competing interests.