[1] Univ Montreal, Fac Nursing, Montreal, PQ H3T 1A8, Canada
[2] CHU St Justine, Res Ctr, Montreal, PQ H3T 1C5, Canada
[3] Women & Childrens Hlth Res Inst, Edmonton, AB T6G 1C9, Canada
[4] Univ Alberta, Fac Med & Dent, Dept Pediat, Edmonton, AB T6G 1C9, Canada
[5] McGill Univ, Ctr Hlth, Montreal, PQ H4A 3J1, Canada
[6] Med Coll Wisconsin, Dept Pediat, Sect Emergency Med, Milwaukee, WI 53226 USA
[7] CHU St Justine, St Justine Hosp, Dept Pediat, Div Emergency Med, Montreal, PQ H3T 1C5, Canada
[8] Childrens Hosp, London Hlth Sci Ctr, London, ON N6A 5W9, Canada
[9] Schulich Sch Med & Dent, London, ON N6A 5C1, Canada
[10] Child Hlth Res Inst, London, ON N6C 2V5, Canada