[1] St Michaels Hosp, Div Neurosurg, Toronto, ON M5B 1W8, Canada
[2] St Michaels Hosp, Injury Prevent Res Off, Toronto, ON M5B 1W8, Canada
[3] Ctr Addict & Mental Hlth, Toronto, ON, Canada
[4] Univ Toronto, Dalla Lana Sch Publ Hlth, Toronto, ON, Canada
[5] Dalhousie Univ, Dept Community Hlth & Epidemiol, Halifax, NS, Canada
[6] Dalhousie Univ, Dept Emergency Med, Halifax, NS, Canada