Footnotes

• Contributors S-LC, GY-KO and SHWY contributed to the writing to this manuscript. All authors revised it critically for important intellectual content and approved the final version to be submitted. The authors have full access to all aspects of the research and writing process and take final responsibility for the paper.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None declared.

• Patient consent for publication Not required.

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