Footnotes

• Contributors AS contributed to conception, initial drafting of the manuscript, critical revision of content and final approval of the manuscript. SC, DBB, AP, AD and EJP contributed to conception, critical revision of content and final approval of manuscript. All authors are in agreement 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 Obtained.

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