Footnotes

• Twitter @TJCoats

• Correction notice This paper has been updated since first published. In Table 1, Column 'Mortality', data value 0.195 has been revised to 0.195%.

• Contributors The article was conceived, written, redrafted and agreed by both authors.

• 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 and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

• Patient consent for publication Not required.

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