1. Department of Otorhinolaryngology, Medical School, Democritus University of Thrace, Alexandroupolis, Greece
2. Department of Statistics, Medical School, Democritus University of Thrace, Alexandroupolis, Greece
3. Department of Otorhinolaryngology, Facial Plastic and Reconstructive Surgery, Städtisches Klinikum Karlsruhe, Karlsruhe, Germany