[1] Med Univ Innsbruck, Innsbruck, Austria
[2] Med Univ Graz, Graz, Austria
[3] Ctr Rheumatol & Spine Dis, Glostrup, Denmark
[4] COPECARE, Glostrup, Denmark
[5] MC Grp Hosp, Lelystad, Netherlands
[6] Esbjerg Cent Hosp, Esbjerg, Denmark
[7] Univ Versailles St Quentin, Boulogne, France
[8] Southend Univ Hosp, Southend On Sea, England
[9] Univ Hosp La Paz, Madrid, Spain
[10] Hosp Rheumat Dis, Haugesund, Norway
[11] Charles Univ Prague, Prague, Czech Republic
[12] Asklepios Med Ctr Bad Abbach, Bad Abbach, Germany
[13] Sapienza Univ Roma, Rome, Italy
[14] Univ Calif Los Angeles, Los Angeles, CA USA
[15] Mayo Clin, Rochester, NY USA
[16] Arcispedale Santa Maria Nuova, Reggio Emilia, Italy
[17] Pomeranian Med Univ, Szczecin, Poland
[18] Norfolk & Norwich Univ Hosp, Norwich, Norfolk, England
[19] Hosp Gen Univ Gregorio Maranon, Madrid, Spain
[20] Lisbon Acad Med Ctr, Lisbon, Portugal
[21] St Elizabeths Med Ctr, Boston, MA USA
[22] Immanuel Krankenhaus Berlin Buch, Berlin, Germany