1. Kimberley Public Health Unit, Derby, WA
2. Nose and Throat Surgeon, Southern Corridor ENT Services, South Fremantle, WA
3. Biostatistical Consulting Service, School of Population Health, University of Western Australia, Crawley, WA
4. Disability Services Commission, West Perth, WA
5. Nose and Throat Surgeon, Department of Otorhinolaryngology – Head and Neck Surgery, Princess Margaret Hospital for Children, Subiaco, WA
6. Centre for Child Health Research, University of Western Australia, Telethon Institute for Child Health Research, Subiaco, WA. Correspondence: Dr Donna B Mak, 189 Royal Street, East Perth, WA 6000.