[1] Univ British Columbia, Dept Med, Vancouver, BC, Canada
[2] St Pauls Hosp, Ctr Hlth Evaluat & Outcome Sci, 588-1081 Burrard St, Vancouver, BC V6Z 1Y6, Canada
[3] Univ Montreal, Montreal, PQ, Canada
[4] St Michaels Hosp, Ctr Res Inner City Hlth, Toronto, ON, Canada
[5] Univ Toronto, Dept Med, Toronto, ON, Canada