1. Department of Primary Care and Population Sciences, Royal Free Hospital School of Medicine, Rowland Hill Street, London NW3 2PF,
2. Department of Public Health Medicine and Epidemiology, University Hospital Queen’s Medical Centre, Nottingham NG7 2UH,
3. Haemophilia Centre and Heamostasis Unit, Royal Free Hampstead NHS Trust, Pond Street, London NW3 2QF