Footnotes

• X @clifford0584

• Contributors GCSL identified appropriate papers to be considered for inclusion, authored a review, edited all reviews for content and is the guarantor. HA, LM, DO’C and JS identified appropriate papers to be considered for inclusion and authored a review. FM identified appropriate papers to be considered for inclusion. EB identified appropriate papers to be considered for inclusion and edited all reviews. TAGS was the monthly editor.

• 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.