1. Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, London, UK
2. Clinical Effectiveness Unit, Royal College of Surgeons of England, London, UK
3. Hull York Medical School, Hull, UK
4. Vascular Surgery, Royal Stoke University Hospital, University Hospitals of North Midlands NHS Trust, Stoke-on-Trent, UK
5. Cambridge Vascular Unit, Cambridge University Hospitals NHS Foundation Trust & Department of Surgery, University of Cambridge, Cambridge, UK