1. From the National Centre for Healthcare Research and Pharmacoepidemiology (F.R., G.C., L.M.), University of Milano-Bicocca, Italy
2. Laboratory of Healthcare Research and Pharmacoepidemiology, Unit of Biostatistics, Epidemiology and Public Health, Department of Statistics and Quantitative Methods (F.R., G.C.), University of Milano-Bicocca, Italy
3. Epidemiologic Observatory, Lombardy Regional Health Service, Milan, Italy (L.M.)
4. University of Milano-Bicocca, Milan, Italy (G.M.); and Policlinico di Monza, Italy (G.M.).