[1] Western Univ, Dept Surg, London, ON, Canada
[2] Univ Minnesota, Dept Urol, Minneapolis, MN USA
[3] Western Univ, Dept Epidemiol & Biostat, London, ON, Canada
[4] Western Univ, Div Urol & Epidemiol & Biostat, St Josephs Hlth Care, Room B4-667, 268 Grosvenor St, London, ON N6A 4V2, Canada