Footnotes

• Twitter @RexWHHui, @Nadirabbas_x

• Contributors RW-HH drafted the initial manuscript. NA, PD and DT provided critical appraisal and revised the manuscript. All authors have reviewed and approved the final version of this 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; externally peer reviewed.