Footnotes

• Contributors MN and AV have made substantial contributions to the article. All the authors have been involved in the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; the drafting the work or revising it critically for important intellectual content; and the final approval of the version to be published. Also, the authors agree to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved.

• 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.