Received: 10 September 2019
Accepted: 5 February 2020
First Online: 13 February 2020
Ethics approval and consent to participate
: This study was approved by the Institutional Review Board (IRB) at Jaseng Hospital of Korean Medicine as ‘review exemption’ because the study did not deal with any case-sensitive information, and accessed only publicly available data from the KNHANES website (JASENG IRB File No. 2017–10-008).
: Not applicable for participants as the data was secondary data accessed as publicly available data from the KNHANES website. Final approval of publication of the manuscript in its current version was given by all authors.
: The authors declare that they have no competing interests.