[1] Med Univ Vienna, Dept Internal Med 3, Dept Rheumatol, Div Rheumatol, A-1090 Vienna, Austria
[2] Hietzing Hosp Vienna, Dept Med 2, Vienna, Austria
[3] Univ Toronto, Mt Sinai Hosp, Rebecca MacDonald Ctr Arthrit & Autoimmun, Toronto, ON M5G 1X5, Canada
[4] Chapel Allerton Hosp, Leeds Teaching Hosp Trust, Leeds, W Yorkshire, England
[5] Arthrit Care, London, England
[6] Leiden Univ, Sch Med, NL-2300 RA Leiden, Netherlands
[7] Humboldt Univ, Charite Hosp, Dept Rheumatol, D-1086 Berlin, Germany
[8] Univ Paris 05, Hop Cochin, Dept Rheumatol, F-75270 Paris 06, France
[9] Univ Cattolica Sacro Cuore, Inst Internal Med & Geriatr, Div Rheumatol, I-00168 Rome, Italy
[10] Med Univ Vienna, Dept Internal Med 1, Div Haematol, A-1090 Vienna, Austria
[11] Karolinska Hosp, Dept Rheumatol, S-10401 Stockholm, Sweden
[12] Diakonhjemmet Hosp, Dept Rheumatol, Oslo, Norway
[13] Univ Autonoma Madrid, Hosp La Paz, Dept Rheumatol, E-28049 Madrid, Spain
[14] Charles Univ Prague, Inst Rheumatol, CR-11636 Prague 1, Czech Republic
[15] Charles Univ Prague, Clin Rheumatol, CR-11636 Prague 1, Czech Republic