Footnotes

• Funding Kooperative Regionaler Rheumazentren (non-profit organisation in rheumatology) and Abbott Immunology Abbott GmbH & Co KG (unrestricted grant).

• Competing interests SK received lecture fees from Abbott, Chugai, Essex, Roche (less than €2000 each). OK received lecture fees from Gilead (€1000), research grants from SIRS-Lab, Germany, honoraria from Abbott (€1000). JE received honoraria for lectures from Wyeth, “RG Gesellschaft für Information und Organisation mbH” and Novartis in 2008 and 2009. MF received lecture fees from Abbott, Chugai, Roche (less than €1000 each). JS received lecture fees from Bayer Healthcare, Bracco and GE (less than $2000 each), honoraria from Bayer Healthcare (less than $8000 each). HPT received speaking fees from Roche, Abbott, Essex, and Wyeth. CK received lecture fees from Abbott, Chugai, Essex, Oxford Immunotec (less than €1000), Roche, Wyeth, honoraria from Essex, UCB, Wyeth and research grants from Abbott, Wyeth.

• Ethics approval This study was conducted with the approval of the ethics committee of the University Hospital of Würzburg, Oberduerrbacher Str. 6, Würzburg, Germany.

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