1. Rigshospitalet; The Nordic Cochrane Centre; Blegdamsvej 9, 7811 Copenhagen Denmark DK-2100
2. Aarhus University Hospital; Otorhinolaryngology and Head & Neck Surgery; 1st Floor, Building 10 Nørrebrogade 44 Aarhus Denmark 8000
3. University of California San Francisco; Department of Clinical Pharmacy and Institute for Health Policy Studies; Suite 420, Box 0613 3333 California Street San Francisco California USA 94143-0613