1. Pediatric and Adolescent Unit, Department of Internal Medicine, University of Pavia, 27100 Pavia, Italy
2. Pediatric Department, Buzzi Children’s Hospital, 20154 Milan, Italy
3. Pediatric Cardiology Unit, Buzzi Children’s Hospital, 20154 Milan, Italy
4. Medical Statistics Unit, Department of Biomedical and Clinical Sciences, University Hospital, University of Milan, 20157 Milan, Italy
5. Department of Biomedical and Clinical Science, University of Milan, 20157 Milan, Italy