Footnotes

• Contributors Both authors contributed equally to the conception, the drafting and the critical revision of this manuscript. Both have accepted 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 for publication Not required.

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

• Data sharing statement No additional data are available.