[1] Ottawa Hosp, Dept Surg, Ottawa, ON, Canada
[2] Ottawa Hosp Res Inst, Clin Epidemiol Program, Ottawa, ON, Canada
[3] Univ Ottawa, Fac Med, Ottawa, ON, Canada
[4] Univ Laval, CHU Quebec, Dept Anesthesia, Quebec City, PQ, Canada
[5] Ottawa Hosp, Dept Anesthesiol & Pain Med, Ottawa, ON, Canada
[6] Ottawa Hosp, Dept Med, Ottawa, ON, Canada
[7] Canadian Blood Serv, Ottawa, ON, Canada
[8] Ottawa Hosp, 501 Smyth Rd,CCW 1667b, Ottawa, ON K1H 8L6, Canada