[1] London Hlth Sci Ctr, Trauma Program, London, ON N6A 5W9, Canada
[2] Univ Western Ontario, Dept Surg, Schulich Sch Med, London, ON N6A 3K7, Canada
[3] Univ Western Ontario, Populat & Community Hlth Unit, London, ON, Canada
[4] Univ Western Ontario, Dept Epidemiol & Biostat, London, ON, Canada
[5] Humboldt Univ, Berlin, Germany
[6] Univ Western Ontario, Dept Sociol, London, ON, Canada
[7] Univ London, Schulich Sch Med, Div Crit Care, London, ON, Canada