1. Rheumatology Unit, Department of Medicine and Public Health, Azienda Ospedaliero-Universitaria and University of Cagliari , Monserrato, Italy
2. Epidemiology Unit, Italian Society for Rheumatology , Milan, Italy
3. Department of Statistics and Quantitative Methods, Division of Biostatistics, Epidemiology and Public Health, University of Milano-Bicocca , Milan, Italy
4. Day Hospital Multidisciplinare Ospedale di Borgomanero e Ambulatori di Reumatologia, ASL Novara , Novara, Italy
5. Academic Rheumatology Centre, Department of Clinical and Biological Sciences, Università degli Studi di Torino , Turin, Italy
6. School of Medicine and Surgery, University of Milano-Bicocca , Milan, Italy