[1] Univ Med Ctr Hamburg Eppendorf, Dept Otorhinolaryngol & Head & Neck Surg, Hamburg, Germany
[2] Inst Med Biostat Epidemiol & Informat IMBEI Mainz, Dept Biometry & Bioinformat, Obere Zahlbacher Str 69, D-55131 Mainz, Germany
[3] Klinikum Mutterhaus Borromaerinnen Mitte, Otorhinolaryngol & Head & Neck Surg, Feldstr 16, D-54290 Trier, Germany