Footnotes

• Handling editor Josef S Smolen

• Contributors DD: writing of the MS, critical review of the MS, approval of the final version. GV: collection of the data, critical review of the MS, approval of the final version. FD: collection of the data, critical review of the MS, approval of the final version. MT: critical review of the MS, approval of the final version. DM: writing of the MS, critical review of the MS, approval of the final version.

• Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

• Competing interests None declared.

• Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.

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