Yi, Sang-Wook
Kim, Se Hwa
Han, Ki Jun
Yi, Jee-Jeon
Ohrr, Heechoul
Article History
Received: 28 June 2019
Revised: 10 November 2019
Accepted: 3 December 2019
First Online: 20 December 2019
Ethics approval and consent to participate
: This study was performed in accordance with the Declaration of Helsinki. This study was approved by the Institutional Review Board of Catholic Kwandong University (CKU-16-01-0301). Informed consent was waived because the anonymised data was used that was provided by NHIS according to strong confidentiality protocol.
: Not applicable.
: The data underlying the results presented in the study are available from the National Health Insurance Service (NHIS) (ExternalRef removed). Applicants to use the data should contact the NHIS (Office of big data operation, +82-33-736-2469) for further information.
: The authors declare no competing interests.
: There was no funding specific for the current work.