[1] McMaster Univ, Dept Clin Epidemiol & Biostat, 501-25 Charlton Ave East, Hamilton, ON L8N 1Y2, Canada
[2] McMaster Univ, St Josephs Healthcare Hamilton, 501-25 Charlton Ave East, Hamilton, ON L8N 1Y2, Canada
[3] McMaster Univ, Dept Med, Hamilton, ON, Canada
[4] Hamilton Hlth Sci, Interdept Div Crit Care, Hamilton, ON, Canada
[5] Univ Toronto, Interdept Div Crit Care Med, Toronto, ON, Canada
[6] Univ Toronto, St Michaels Hosp, Toronto, ON, Canada
[7] Monash Med Ctr, Intens Care Unit, Melbourne, Vic, Australia
[8] Queens Univ, Dept Crit Care Med, Kingston, ON, Canada
[9] Univ Toronto, Univ Hlth Network, Toronto, ON, Canada
[10] Univ Toronto, Mt Sinai Hosp, Toronto, ON, Canada
[11] Univ British Columbia, Dept Med, Div Crit Care, Vancouver, BC, Canada
[12] Duke Univ, Duke Clin Res Inst, Durham, NC USA
[13] Univ Laval, Div Crit Care Med, Dept Anesthesiol & Crit Care Med, Quebec City, PQ, Canada
[14] McMaster Univ, Dept Clin Epidemiol & Biostat, 25 Main St West,Suite 2000,20th Floor, Hamilton, ON L8P 1H1, Canada
[15] St Josephs Healthcare Hamilton, Ctr Evaluat Med, 25 Main St West,Suite 2000,20th Floor, Hamilton, ON L8P 1H1, Canada