[1] Univ Alberta, Dept Lab Med & Pathol, Edmonton, AB T6G 2R3, Canada
[2] Univ Calgary, Cumming Sch Med, Dept Pediat, Sect Pediat Emergency Med & Gastroenterol, Calgary, AB T3B 6A8, Canada
[3] Univ Calgary, Dept Emergency Med, Sect Pediat Emergency Med & Gastroenterol, Cumming Sch Med, Calgary, AB T3B 6A8, Canada
[4] Univ Calgary, Alberta Childrens Hosp, Paediat Emergency Res Team, Calgary, AB T3B 6A8, Canada
[5] Univ Ottawa, Dept Pediat, Ottawa, ON K1H 8L1, Canada
[6] Univ Ottawa, Dept Emergency Med, Ottawa, ON K1H 8L1, Canada
[7] Univ Montreal, Ctr Hosp Univ Ste Justine, Dept Pediat, Div Paediat Emergency Med, Montreal, PQ H3T 1C5, Canada
[8] Schulich Sch Med & Dent, Dept Internal Med, London, ON N6A 5W9, Canada
[9] Schulich Sch Med & Dent, Dept Epidemiol, London, ON N6A 5W9, Canada
[10] Schulich Sch Med & Dent, Dept Biostat, London, ON N6A 5W9, Canada
[11] Univ Toronto, Hosp Sick Children, Div Paediat Emergency Med, Toronto, ON M5G 1X8, Canada
[12] Univ Toronto, Div Emergency Med, Res Inst, Hosp Sick Children, Toronto, ON M5G 1X8, Canada
[13] Univ Toronto, Hosp Sick Children, Res Inst, Div Clin Pharmacol & Toxicol, Toronto, ON M5G 1X8, Canada
[14] Univ Calgary, Cumming Sch Med, Dept Pediat, Calgary, AB T3B 6A8, Canada
[15] Univ Alberta, Stollery Childrens Hosp, Dept Pediat, Fac Med & Dent,Women & Childrens Hlth Res Inst, Edmonton, AB T6G 2R3, Canada
[16] Publ Hlth Lab, Alberta Precis Lab, Edmonton, AB T6G 2J2, Canada