1. Clinical Rheumatology Unit, ASST Gaetano Pini-CTO, Department of Clinical Sciences & Community Health, Università degli Studi di Milano, Milano, Italy
2. Lab of Medical Statistics, Biometry and Epidemiology “GA Maccacaro”, Department of Clinical Sciences & Community Health, Università degli Studi di Milano, Milano, Italy
3. Department of Biomedical and Clinical Sciences “L. Sacco”, Università degli Studi di Milano, Milano, Italy