1. Department of Otorhinolaryngology, Head & Neck Surgery, University Medicine Halle, Halle (Saale), Germany
2. Department of Internal Medicine, University Medicine Halle, Halle (Saale), Germany
3. Robert Bosch Society for Medical Research, Robert Bosch Hospital, Stuttgart, Germany
4. Institute for Clinical Epidemiology and Applied Biometry, University of Tübingen, Tübingen, Germany
5. Coordination Centre for Clinical Trials, Martin Luther University Halle-Wittenberg, Halle (Saale), Germany
6. Scientific Institute for Applied Oto-Rhino-Laryngology of the German Professional Association of ENT Surgeons, Bad Bramstedt, Germany
7. Department of Laboratory Medicine, Central Laboratory, University Hospital Halle, Halle (Saale), Germany
8. Department of Otorhinolaryngology/Plastic Surgery, SRH Zentralklinikum Suhl, Suhl, Germany
9. ENT Practice, Bad Neustadt, Germany
10. ENT Department, AMEOS Clinic Halberstadt, Halberstadt, Germany
11. Department of Otorhinolaryngology, Head and Neck Surgery, Plastic Surgery, University Hospital of Giessen and Marburg, Giessen, Germany
12. Department of Otorhinolaryngology, Head and Neck Surgery “Otto Körner,” Rostock University Medical Center, Rostock, Germany
13. ENT Practice, Bad Schönborn, Germany
14. ENT Department, Hospital St. Georg gGmbH, Leipzig, Germany
15. Department of Otorhinolaryngology, Head and Neck Surgery, Technical University Dresden, Faculty of Medicine and University Hospital Carl Gustav Carus, Dresden, Germany
16. Department of Otorhinolaryngology, Goethe University Frankfurt, University Hospital, Frankfurt, Germany
17. Department Otorhinolaryngology/Plastic Surgery, SRH Wald-Klinikum Gera gGmbH, Gera, Germany
18. Department of Otorhinolaryngology, Head and Neck Surgery, St. Elisabeth Hospital, Ruhr University Bochum, Bochum, Germany
19. Department of Otorhinolaryngology, Jena University Hospital, Jena, Germany
20. Department of Otorhinolaryngology and Head and Neck Surgery, University of Erlangen-Nuremberg, Erlangen, Germany
21. Department of Otorhinolaryngology, University of Regensburg, Regensburg, Germany
22. Department of Otorhinolaryngology, Head and Neck Surgery, Heinrich-Braun-Klinikum gGmbH, Zwickau, Germany