[1] Queens Univ, Dept Emergency Med, Kingston, ON, Canada
[2] Univ Washington, Dept Biostat, Seattle, WA 98195 USA
[3] Univ Toronto, St Michaels Hosp, Li Ka Shing Knowledge Inst, Rescu, Toronto, ON, Canada
[4] Oregon Hlth & Sci Univ, Dept Surg, Portland, OR 97201 USA
[5] Univ Ottawa, Dept Emergency Med, Ottawa, ON, Canada