Footnotes

• Contributors All authors (APD, RPJB, MLG and APK) contributed substantially to the conception, drafting of this work, as well as its revision for important intellectual content. Both authors approved the manuscript and are accountable for its accuracy or integrity.

• Competing interests None declared.

• Provenance and peer review Commissioned; externally peer reviewed.

• Author note Any references listed which include a * are deemed important references for this paper.