Footnotes

• Contributors AP conceived and wrote this paper.

• 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 AP reports grants from NIHR and NIHR School of Primary Care Research and occasionally receives expenses for teaching evidence-based medicine.

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

• Patient consent for publication Not required.