1. Department of Humanities and Social Science, University of Sassari, 07100 Sassari, Italy
2. Clinical Epidemiology and Medical Statistics Unit, Department of Medicine, Surgery and Pharmacy, University of Sassari, 07100 Sassari, Italy
3. Department of Medicine, Surgery and Pharmacy, University of Sassari, 07100 Sassari, Italy
4. Department of Medicine and Surgery, University of Milano-Bicocca, 20900 Monza, Italy