[1] Univ Saskatchewan, Dept Emergency Med, 103 Hosp Dr, Saskatoon, SK S7N 0W8, Canada
[2] Univ Sherbrooke, Dept Med Familiale & Med Urgence, Sherbrooke, PQ, Canada
[3] Univ Ottawa, Dept Emergency Med, Ottawa, ON, Canada
[4] Univ Ottawa, Sch Epidemiol & Publ Hlth, Ottawa, ON, Canada
[5] Ottawa Hosp, Clin Epidemiol Program, Res Inst, Ottawa, ON, Canada
[6] Dalhousie Univ, Dept Emergency Med, Halifax, NS, Canada
[7] Univ Toronto, Fac Med, Schwartz Reisman Emergency Med Inst, Toronto, ON, Canada