1ENT Clinic, Ghent University Hospital, Ghent, Belgium
2ENT Clinic, Mannheim University Hospital, Mannheim
3Department for Medical Statistics, Informatics and Epidemiology, University of Cologne, Cologne
4ENT Clinic, University Hospital Großhadern, Munich
5ENT Clinic, Ulm University Hospital, Ulm
6ENT Clinic, Dresden University Hospital, Dresden
7ENT Clinic, Dortmund Hospital, Dortmund
8ENT Clinic, Münster University Hospital, Münster, Germany
Professor Dr med. Claus Bachert, MD PhD, ENT Clinic, Ghent University Hospital, B-9000 Ghent. Belgium
Accepted for publication 10 September 2002