Footnotes

• Handling editor Josef S Smolen

• Contributors SM and CM contributed to the design of the study and manuscript preparation. PD and SM collected and analysed the data and revised the manuscript. EB, AM, FB contributed to the collection of data and manuscript review.

• 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.

• Patient consent for publication Not required.

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