Footnotes

• Contributors SS contributed to concept, review of literature and drafting of the manuscript. PS contributed to concept and design; critical revision of the manuscript.

• 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.

• Provenance and peer review Commissioned; internally peer reviewed.