[1] Univ Liege, Bone & Cartilage Unit, Liege, Belgium
[2] Univ Liege, WHO, Collaborating Ctr Publ Hlth Aspects Osteoarticula, Dept Epidemiol & Publ Hlth, Liege, Belgium
[3] Railway Hosp, Dept Internal Med, Warsaw, Poland
[4] Nuestra Sra Candelaria Hosp, Consultas Externas Reumatol, Tenerife, Spain
[5] Univ Debrecen, Med & Hlth Sci Ctr, Dept Obstet & Gynaecol, H-4012 Debrecen, Hungary
[6] N London Clin Studies Ctr, London, England
[7] Vittorio Emanuele Hosp, Catania, Italy
[8] Hop Cochin, Dept Rheumatol, F-75674 Paris, France
[9] Ruhr Univ Bochum, St Josef Hosp, Sch Med, Dept Med, D-4630 Bochum, Germany
[10] Cent Hosp Hillerod, Dept Clin Physiol, Hillerod, Denmark
[11] Sir Charles Gairdner Hosp, Dept Med, Perth, WA, Australia
[12] Jan Palfijn Zeikenhuis, Dept Rheumatol, Merksem, Belgium
[13] Univ Hosp Geneva, Dept Internal Med, Div Bone Dis, Geneva, Switzerland
[14] Univ Hosp Geneva, Sch Dent, Geneva, Switzerland
[15] Hop Edouard Herriot, Dept Rheumatol & Bone Dis, Lyon, France