1. Otorhinolaryngology Service; Department of Oncology; San Luigi Gonzaga Hospital, University of Turin; Turin Italy
2. Otorhinolaryngology Service; Martini Hospital; Turin Italy
3. Otorhinolaryngology Service; Vittorio Veneto Hospital; Vittorio Veneto Treviso Italy
4. L'altrastatistica srl; Consultancy and Training; Biostatistics Office; Rome Italy
5. Department of Clinical and Biological Sciences; University of Turin; Turin Italy