Footnotes

• Handling editor Josef S Smolen

• Contributors All authors contributed to the planning, conduct and reporting of the work described in the article. EI is responsible for the overall content.

• Funding The study was supported by internal funds at the REMEDY Center for treatment of Rheumatic and Musculoskeletal Diseases, Diakonhjemmet Hospital, Oslo, Norway.

• Competing interests EI has nothing to declare. AGS has received speaker fees from Merck/Schering-Plough, BMS, UCB, Pfizer/Wyeth, Novartis, Lilly and Women’s College Hospital, Toronto, Canada. AMK has received speaker fees from Abbvie, Sanofi, Boehringer-Ingelheim and support for attending meetings/travel from Abbvie.

• Patient and public involvement Patients and/or the public were involved in the design, or conduct, or reporting, or dissemination plans of this research. Refer to the Methods section for further details.

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

• Supplemental material This content has been supplied by the author(s). It has not been vetted by BMJ Publishing Group Limited (BMJ) and may not have been peer-reviewed. Any opinions or recommendations discussed are solely those of the author(s) and are not endorsed by BMJ. BMJ disclaims all liability and responsibility arising from any reliance placed on the content. Where the content includes any translated material, BMJ does not warrant the accuracy and reliability of the translations (including but not limited to local regulations, clinical guidelines, terminology, drug names and drug dosages), and is not responsible for any error and/or omissions arising from translation and adaptation or otherwise.