Footnotes

• Contributors GG is responsible for the overall content of the article, as well as for submitting and acting as the correspondent. GG, OP-R and UD are equal contributors to the planning, conduct, and reporting of the work described in the article, as well as to the manuscript writing.

• Funding The study sponsors have not had any involvement in the study design; in the collection, analysis and interpretation of the data; in the writing of the report; and in the decision to submit the paper for publication.

• Competing interests None declared.

• Provenance and peer review Commissioned; externally peer reviewed.