Footnotes

• Contributors NA and JW conceived the manuscript. NA drafted the manuscript. Both authors reviewed the manuscript and 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 None declared.

• Patient consent Not required.

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

• Data sharing statement No additional data are available.