[1] Univ Western Ontario, Div Nephrol, London, ON, Canada
[2] Univ Western Ontario, Dept Epidemiol & Biostat, London, ON, Canada
[3] Univ British Columbia, St Pauls Hosp, Dept Nephrol, Vancouver, BC V5Z 1M9, Canada
[4] Cleveland Clin Fdn, Dept Hypertens & Nephrol, Cleveland, OH 44195 USA