[1] Univ Ottawa, Ottawa Hosp Res Inst, Dept Med, Ottawa, ON, Canada
[2] Univ Calgary, Dept Med, Calgary, AB, Canada
[3] Univ Ottawa, Ottawa Hosp Res Inst, Ottawa Hosp, Fac Med,Dept Med,Clin Epidemiol Program,Div Hemato, 501 Smyth Rd,Box 201A,Room L2260, Ottawa, ON K1H 8L6, Canada