[1] UCL, Epidemiol & Publ Hlth, London, England
[2] UCL, Ctr Med Imaging, London, England
[3] South Tyne & Wear Screening Ctr, Gateshead, England
[4] Univ Durham, Sch Med Pharm & Hlth, Durham, England
[5] Univ Oxford, Nuffield Dept Populat Hlth, Oxford, England