1. Department of Pediatrics, IRCCS Policlinico San Matteo, University of Pavia, Italy
2. Navy Hospital, Medicine Department, La Spezia, Italy
3. Biometry and Clinical Epidemiology Service, IRCCS Policlinico San Matteo, Pavia, Italy
4. Istituto Giannina Gaslini, Genoa, Italy
5. Department of Pediatrics, University of Catania, Italy
6. Allergy, Head?Neck Department, San Martino Hospital, Genoa, Italy