Footnotes

• SWL, JMY and IKY are joint first authors.

• Contributors Dr DKY had full access to all of the data in the study and took responsibility for the integrity of the data and the accuracy of the data analysis. All authors approved the final version before submission. Conception and design: SWL and DKY; analysis and interpretation of the data: SWL, JMY and DKY; drafting of the article: JMY, IKY, AÖY and DKY; critical revision of the article for important intellectual content: SWL, JMY, IKY, EKH, JYC, MSK, JIS and DKY; final approval of the article: all authors; statistical expertise: SYM, SWL and DKY; administrative, technical or logistic support: SWL and DKY; collection and assembly of data: DKY. DKY is guarantor. The corresponding author attests that all listed authors meet authorship criteria and that no others meeting the criteria have been omitted.

• Funding This work was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (NRF2019R1G1A109977912).

• Disclaimer The funders had no role in the design, analyses or interpretation of the study.

• Competing interests None declared.

• Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting or dissemination plans of this research.

• Provenance and peer review Not commissioned; internally peer reviewed.