Footnotes

• Contributors JK and FB are responsible for the overall content as guarantor and managed the evolution of the article. The article was written and revised by JK, FB, JB and AT. All authors provided substantial information and editorial assistance while drafting the article and have all provided their final approval for its publication.

• Funding This research received no specific grant 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.