[1] Charite, Dept Rheumatol & Clin Immunol, Charitepl 1, D-10117 Berlin, Germany
[2] Univ Med Ctr Utrecht, Dept Rheumatol & Clin Immunol, Utrecht, Netherlands
[3] Vrije Univ Amsterdam, Med Ctr, Amsterdam Rheumatol & Immunol Ctr, Amsterdam, Netherlands
[4] Vrije Univ Amsterdam Med Ctr, Med Humanities, Amsterdam, Netherlands
[5] Vrije Univ Amsterdam, Med Ctr, Dept Epidemiol & Biostat, Amsterdam, Netherlands
[6] Patient Res Partner, Mol, Belgium
[7] Univ Genoa, Dept Internal Med, Res Lab, I-16126 Genoa, Italy
[8] Univ Genoa, Acad Div Clin Rheumatol, Genoa, Italy
[9] Southend Univ Hosp NHS Fdn Trust, Westcliff On Sea, Essex, England
[10] Univ Manchester, Inst Inflammat & Repair, Ctr Musculoskeletal Res, Arthrit Res UK Ctr Epidemiol, Manchester, Lancs, England
[11] Univ Utrecht, Dept Clin & Hlth Psychol, Utrecht, Netherlands
[12] Leiden Univ, Med Ctr, Dept Rheumatol, Leiden, Netherlands
[13] Salisbury Fdn Trust NHS Hosp, Salisbury, Wilts, England
[14] Aarhus Univ Hosp, Dept Rheumatol, DK-8000 Aarhus, Denmark
[15] German Rheumatism Res Ctr, Epidemiol Unit, Berlin, Germany
[16] Hop Univ Paris Sud, AP HP, Dept Rheumatol, Le Kremlin Bicetre, France
[17] Univ Paris 11, INSERM, U1184, Le Kremlin Bicetre, France
[18] Univ Manchester, Fac Med & Hlth Sci, Manchester, Lancs, England
[19] Copenhagen Univ Hosp, Parker Inst, Dept Rheumatol, Bispebjerg, Denmark
[20] Copenhagen Univ Hosp, Parker Inst, Dept Rheumatol, Frederiksberg, Denmark
[21] Deutsche Reuma Liga, Bonn, Germany
[22] Oregon Hlth & Sci Univ, Div Infect Dis, Portland, OR 97201 USA