Footnotes

• Contributors JH and SM planned and contributed to the manuscript equally in ideas and writing. The revision and final submission of the manuscript was made by JH and SM jointly.

• 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 to declare.

• Patient consent for publication Not required.

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