Footnotes

• Contributors GC (first author) did the literature review and drafted the article. EW supervised writing of article, edited and formatted for submission, made changes for resubmission.

• 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.

• Provenance and peer review Not commissioned; externally peer-reviewed.