[1] Univ Las Palmas Gran Canaria, Hosp Gran Canaria Dr Negrin, Las Palmas Gran Canaria 35011, Spain
[2] Jyvaskyla Cent Hosp, Jyvaskyla, Finland
[3] Medcare OY, Aanekoski, Finland
[4] Spanish Fdn Rheumatol, Res Unit, Madrid 28001, Spain
[5] Hosp Sierrallana, Torrelavega 39300, Spain
[6] King Christian Xth Hosp, DK-6300 Grasten, Denmark
[7] Satakunta Cent Hosp, Rauma 26100, Finland
[8] Hop Lapeyronie, F-34295 Montpellier 5, France
[9] Charite Univ Med Berlin, D-10117 Berlin, Germany
[10] Waterford Reg Hosp, Waterford, Ireland
[11] Univ Cattolica Sacro Cuore, I-00168 Rome, Italy
[12] Med Spectrum Twente, NL-7513 ER Enschede, Netherlands
[13] Med Univ Lublin, PL-20095 Lublin, Poland
[14] Szpital Wojewodzki Jana Biziela, PL-85104 Bydgoszcz, Poland
[15] Hosp Gen Castellon, Castellon de La Plana 12004, Spain
[16] Hudiksvall Med Clin, S-82481 Hudiksvall, Sweden
[17] Kings Coll Hosp London, Strand, London WC2R 2LS, England
[18] Selcuk Univ, Meram Med Fac, TR-42090 Konya, Turkey
[19] Inst Rheumatol, Niska Banja 18205, Serbia
[20] Taylor Hosp, Ridley Pk, PA 19078 USA
[21] Hosp San Juan Bautista, Catamarca, Argentina
[22] New York Univ Hosp Joint Dis, New York, NY 10003 USA