Funding for this research was provided by:
Korea national research foundation (NRF-2019R1G1A109408)
Received: 6 February 2020
Accepted: 25 April 2020
First Online: 2 May 2020
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board of Yonsei University, Republic of Korea (no. CR318352). Anonymous and de-identified information was used for analysis; therefore, informed consent was not obtained.
: Not applicable.
: The authors declare that they have no competing interests.
: The study sponsor was not involved in the design of the study; the collection, analysis, and interpretation of data; writing the report; or the decision to submit the report for publication.