1. London School of Hygiene and Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK and Honorary Lecturer, The Royal College of Surgeons of England, 35-43 Lincoln’s Inn Fields, London WC2A 3PE, UK
2. Clinical Effectiveness and Evaluation Unit, Royal College of Physicians, 11 St Andrews Place, London NW1 4LE, UK
3. Trauma Unit, University Hospital of Wales, Heath Park, Cardiff CF14 4XW, UK
4. London School of Hygiene and Tropical Medicine, 15-17 Tavistock Place, London WC1H 9SH, UK and Director of Clinical Effectiveness Unit, The Royal College of Surgeons of England, 35-43 Lincoln’s Inn Fields, London WC2A 3PE, UK