1. From the University of Manchester arc Epidemiology Unit (M.E.-M., Y.A.), Department of Vascular Surgery (H.B., M.W.), Rheumatism Research Centre (Y.A., R.M.B., I.N.B.), and Department of Medicine (P.N.D., M.M.), Manchester Royal Infirmary, Central Manchester and Manchester Children’s University Hospitals NHS Trust, Manchester, UK.