Footnotes

• Contributors PKY: conception, review of literature, finalising the manuscript. VK: review of literature, writing and revising the manuscript. All authors have read and 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.

• Patient consent for publication Not required.

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