Footnotes

• Contributors All authors have equal contribution to the article.

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

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