Footnotes

• Contributors CTS and MB wrote the initial draft and OFN revised it. All three authors approved the final manuscript.

• 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 Norheim is a co-author on several GBD papers.

• Competing interests None declared.

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

• Patient consent for publication Not required.