1. Faculty of Health and Life Sciences, Northumbria University , Newcastle Upon Tyne , UK
2. Department of Medical Statistics, London School of Hygiene and Tropical Medicine , London , UK
3. Department of Cardiac Surgery, John Radcliffe Hospital, Oxford University Hospitals , Oxford , UK
4. School of Social Sciences, Humanities and Law, Teesside University , Middlesbrough , UK
5. Department of Surgery and Cancer, Imperial College , London , UK
6. Imperial Vascular Unit, Imperial Healthcare NHS Trust , London , UK