[1] Univ British Columbia, Vancouver Gen Hosp, Dept Med, Div Crit Care Med, Vancouver, BC, Canada
[2] Univ British Columbia, Vancouver Gen Hosp, Div Neurosurg, Dept Surg, Vancouver, BC, Canada
[3] Univ British Columbia, Vancouver Gen Hosp, Fac Med, Vancouver, BC, Canada
[4] Univ British Columbia, Vancouver Gen Hosp, Dept Surg, Div Trauma Surg, Vancouver, BC, Canada
[5] Univ British Columbia, Vancouver Gen Hosp, Dept Anaesthesiol Pharmacol & Therapeut, Vancouver, BC, Canada
[6] Univ British Columbia, Vancouver Coastal Hlth Res Inst, Ctr Clin Epidemiol & Evaluat, Vancouver, BC, Canada