Footnotes

• Twitter @carlheneghan, @krmahtani

• Contributors CH wrote the first draft, KRM provided edits. Both authors approved the final draft.

• 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.

• Disclaimer The views expressed are those of the authors and not necessarily those of the NHS, the NIHR or the Department of Health and Social Care.

• Competing interests CH and KRM are supported by the NIHR School for Primary Care ResearchEvidence Synthesis Working group (NIHR SPCR ESWG project 390). CH isalso 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. KRM is an associate editor of BMJ EBM.

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