[1] OXON Epidemiol Ltd, London E17 7DH, England
[2] UCL, Div Surg & Intervent Sci, London WC1E 6BT, England
[3] Univ London Imperial Coll Sci Technol & Med, Dept Primary Care & Social Med, London, England
[4] Univ Coll Dublin, Sch Med & Med Sci, Dublin 2, Ireland
[5] GlaxoSmithKline SA, Dept Med, Madrid, Spain
[6] Univ Hosp Vienna, Dept Urol, Vienna, Austria