1. Department of Otorhinolaryngology, Head and Neck Surgery, Sint Antonius Hospital, Nieuwegein, The Netherlands
2. Department of Otorhinolaryngology, Head and Neck surgery, UMC Utrecht, Utrecht, The Netherlands
3. Department of Otorhinolaryngology, Head and Neck Surgery, UMC Groningen, Groningen, the Netherlands
4. Department of Otorhinolaryngology, Head and Neck Surgery, Erasmus MC, Rotterdam, The Netherlands
5. Department of Pulmonology, St. Antonius Hospital, Nieuwegein, The Netherlands