[1] Gaetano Pini Inst, Milan, Italy
[2] Italian Soc Rheumatol, Epidemiol Unit, Milan, Italy
[3] Univ Genoa, Dept Internal Med, Res Lab, I-16126 Genoa, Italy
[4] Univ Genoa, Dept Internal Med, Acad Unit Clin Rheumatol, I-16126 Genoa, Italy
[5] Univ Ferrara, Dept Med Sci, I-44100 Ferrara, Italy
[6] IRCCS San Matteo Fdn, Div Rheumatol, Pavia, Italy
[7] Univ Florence, Dept Internal Med, I-50121 Florence, Italy
[8] San Camillo Hosp, Dept Rheumatol, Rome, Italy