1. Laboratory of Healthcare Research and Pharmacoepidemiology, Unit of Biostatistics, Epidemiology, and Public Health, Department of Statistics and Quantitative Methods, University of Milano-Bicocca, Milan, Italy
2. Institute of Respiratory Diseases, University of Sassari, Sassari, Italy
3. Unit of Epidemiology and Medical Statistics, University of Verona, Verona, Italy
4. Division of Pneumology, “Guido Salvini” Hospital, Garbagnate Milanese, Italy
5. Operative Unit of Territorial Health Services, Region Lombardia, Milan, Italy