1. Otorhinolaryngology Department, S. Francesco Hospital, ASL 3, Nuoro, Italy
2. Immunology Department, AOU Cagliari, Italy
3. Pathology Department, S. Francesco Hospital, ASL 3, Nuoro, Italy
4. Epidemiology and Medical Statistics Unit, Medical Education and Professional Development Unit, Department of Biomedical Sciences, University of Sassari-Research, AOU Sassari, Italy