Footnotes

• Twitter @ChaviniR

• Contributors CR and JP contributed equally to this work. Both CR and JP jointly conceived the idea, undertook the literature search, performed critical analysis and wrote the initial manuscript. Both authors approved the final 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.

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