1. National Centre for Healthcare Research and Pharmacoepidemiology, Department of Statistics and, Quantitative Methods, University of Milano-Bicocca, Milan, Italy
2. Department of Statistics and Quantitative Methods, Division of Biostatistics, Epidemiology and Public Health, Laboratory of Healthcare Research and Pharmacoepidemiology, University of Milano-Bicocca, Milan, Italy
3. Sciences and Public Health, University of PadovaUnit of Biostatistics, Epidemiology and Public Health, Department of Cardio-Thoraco-Vascular, Padova, Italy