[1] Univ Montreal, Dept Med, Montreal, PQ, Canada
[2] McMaster Univ, Dept Clin Epidemiol & Biostat, Hamilton, ON, Canada
[3] Hamilton Hlth Sci, Populat Hlth Res Inst, Hamilton, ON, Canada
[4] McMaster Univ, Hamilton, ON, Canada
[5] Queens Univ, Dept Anesthesiol & Perioperat Med, Kingston, ON, Canada
[6] Cape Breton Reg Hosp, Cape Breton, NS, Canada
[7] Univ Calgary, Div Cardiol, Calgary, AB, Canada
[8] Univ Manitoba, Thorac Surg Sect, Dept Surg, Winnipeg, MB, Canada
[9] Univ Alberta, Dept Med, Edmonton, AB, Canada
[10] McMaster Univ, Dept Med, Hamilton, ON, Canada
[11] Dalhousie Univ, Dept Med, Halifax, NS, Canada
[12] McGill Univ, Ctr Hlth, Div Gen Internal Med, Montreal, PQ, Canada
[13] Cleveland Clin, Inst Anesthesiol, Dept Outcomes Res, Cleveland, OH 44106 USA
[14] Univ Ottawa, Dept Anesthesiol & Pain Med, Ottawa, ON, Canada
[15] Ottawa Hosp, Res Inst, Clin Epidemiol Program, Ottawa, ON, Canada