Footnotes

• Twitter @carlheneghan

• Contributors AP wrote the first draft and CH contributed to this draft and provided intellectual input. Both authors approved the final version.

• 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, grants from NIHR School of Primary Care Research (NIHR SPCR ESWG project 390) and occasionally receives expenses for teaching Evidence-Based Medicine. AP is also an Associate Editor of the BMJ Evidence-Based Medicine.CH is supported by the NIHR School for Primary Care Research, Evidence Synthesis Working group (NIHR SPCR ESWG project 390). CH is also supported by the NIHR Oxford Biomedical Research Centre, Oxford University Hospitals NHS Foundation Trust, an NIHR Senior Investigator and Editor in Chief of BMJ Evidence-Based Medicine.

• Provenance and peer review Commissioned; internally peer reviewed.