Footnotes

• Contributors GJ wrote the first manuscript draft and no honorarium was perceived for that. GJ also conceived the study and interpreted the data. FZ participated to the writing of the first manuscript draft, collected data and interpreted them. FA collected data and participated to the design of the study. DLD designed the study, analysed and interpreted the data, critically supervised the paper preparation and was responsible for the general study organisation. All authors reviewed the manuscript for important intellectual contents and approved the final version. All authors agreed to be accountable for all aspects of the work.

• Competing interests None declared.

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