Footnotes

• Contributors All authors contributed equally to the concept and development of 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.

• Disclaimer The views expressed in this publication are those of the authors and not necessarily those of the NIHR or the Department of Health and Social Care.

• Competing interests None declared.

• Provenance and peer review Commissioned; internally peer reviewed.