1. Clinical Effectiveness Unit, The Royal College of Surgeons of England, London, England, UK
2. Public Health and Policy, London School of Hygiene and Tropical Medicine, London, England, UK
3. Division of Community Based Sciences, University of Glasgow, Glasgow, Scotland, UK
4. ENT Department, Milton Keynes General NHS Trust, Milton Keynes, Buckinghamshire, England, UK
5. Department of Otolaryngology, Ipswich Hospital NHS Trust, Ipswich, Suffolk, UK