Footnotes

• Contributors The three authors are justifiably credited with authorship according to the ICMJE guidelines: (1) substantial contributions to conception and design, acquisition of data, or analysis and interpretation of data; (2) drafting the article or revising it critically for important intellectual content and (3) final approval of the version to be published. All the authors meet conditions 1, 2 and 3.

• Disclosure The authors have no proprietary interest in the products described in this article. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.

• Funding This research received no specific grant from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None.

• Patient consent Obtained.

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