Footnotes

• Twitter @drsusiec, @MikeTonkins

• Contributors HC: initial article search, organisation of team, literature review, article selection and editing. FS, SC, JL, MW and AR: literature review, article selection, critical appraisal and article summary. MT: critical appraisal and article summary. GP: editing of the article, organisation of team and article selection.

• 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.

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