[1] Univ Genoa, Dept Internal Med, Res Lab, Genoa, Italy
[2] Univ Genoa, Dept Internal Med, Acad Div Clin Rheumatol, Genoa, Italy
[3] Ghent Univ Hosp, Dept Rheumatol, Ghent, Belgium
[4] Univ Ghent, Dept Internal Med, Ghent, Belgium
[5] Univ Manchester, Manchester Acad Hlth Sci Ctr, Ctr Musculoskeletal Res, Manchester, Lancs, England
[6] Schon Klin Hamburg Eilbek, Hamburg Ctr Pediat & Adolescent Rheumatol, Hamburg, Germany
[7] Univ Ghent, Dept Publ Hlth, Biostat Unit, Ghent, Belgium
[8] Univ Hosp Zurich, Dept Rheumatol, Zurich, Switzerland
[9] Univ Milan, Inst Gaetano Pini, Dept Clin Sci & Community Hlth, Div Rheumatol, Milan, Italy
[10] Univ Ziekenhuis Brussel, Dept Dermatol, Brussels, Belgium
[11] Vrije Univ Brussel, Dept Dermatol, Brussels, Belgium
[12] Univ Libre Bruxelles, CHU Brugmann, Dept Immunol & Allergol CIA, Brussels, Belgium
[13] Kerckhoff Clin Bad Nauheim, Dept Rheumatol & Clin Immunol, Bad Nauheim, Germany
[14] Justus Liebig Univ Giessen, Dept Internal Med & Rheumatol, Giessen, Germany
[15] Univ Sapienza Rome, Dept Internal Med & Med Specialities, Rome, Italy