Footnotes

• Twitter @prentice_joanna

• Contributors JP and TC conceived the idea. JP, LH and TC collected data. LH and JP literature review. MF provided review of paper and all data analysis.

• 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.