1. From the Department of Social Medicine (R.M.M., S.E., G.D.S., S.W., S.F., D.G.), University of Bristol, Bristol, UK; The Vascular Noninvasive Screening and Diagnostic Centre (M.G.), London, UK; Department of Neurovascular Sciences (A.N.N., N.G.), The Cyprus Institute of Neurology and Genetics, Nicosia; and Department of Surgery (J.M.P.H.), University of Bristol, Bristol Royal Infirmary, UK.