[1] Univ Naples 2, Naples, Italy
[2] Univ Pisa, Dept Internal Med, Clin Immunol Unit, I-56100 Pisa, Italy
[3] Univ Pisa, Dept Internal Med, Rheumatol Unit, I-56100 Pisa, Italy
[4] Univ Florence, Ist Clin Med 4, I-50121 Florence, Italy
[5] Univ Manchester, Manchester M13 9PL, Lancs, England
[6] Univ Dundee, Ninewells Hosp & Med Sch, Dundee DD1 9SY, Scotland
[7] Royal Free Acad Hosp, London, England
[8] Univ Zurich Hosp, CH-8091 Zurich, Switzerland
[9] Univ Pecs, Pecs, Hungary
[10] Univ Ioannina, GR-45110 Ioannina, Greece
[11] Univ Ancona, I-60128 Ancona, Italy
[12] Univ Aquila, I-67100 Laquila, Italy
[13] Istanbul Univ, Istanbul, Turkey
[14] Royal Natl Hosp Rheumat Dis, Bath BA1 1RL, Avon, England
[15] Univ Paris 07, Paris, France
[16] Herlev Hosp, Rheumatol Unit, DK-2730 Herlev, Denmark
[17] Univ Milan, I-20122 Milan, Italy
[18] Charles Univ Prague, Prague, Czech Republic
[19] Univ Lodz, PL-90131 Lodz, Poland
[20] Univ Padua, I-35100 Padua, Italy
[21] Univ Nijmegen Hosp, NL-6500 HB Nijmegen, Netherlands
[22] Natl Tech Univ Athens, Athens, Greece