Footnotes

• Contributors Acquisition, analysis and interpretation of data: AT, GA, LM, AS, FS, AR and AP; drafting the work or revising it critically for important intellectual content: AT and AP; final approval of the version published, 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: AT, GA, LM, AS, FS, AR and AP.

• 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 and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

• Patient consent for publication Obtained.

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