title: Variability and predictability of large-volume red blood cell transfusion in cardiac surgery: a multicenter study.
abstract: BACKGROUND
  In cardiac surgery, excessive blood loss requiring large-volume red blood cell (RBC) transfusion is a common occurrence that is associated with significant morbidity and mortality. The objectives of this study were to measure the interinstitution variation and predictability of large-volume RBC transfusion.
  
  
  METHODS
  Data were retrospectively collected on 3500 consecutive cardiac surgical patients at seven Canadian hospitals during 2004. The crude and risk-adjusted institutional odds ratios (ORs) for large-volume (>or=5 U) RBC transfusion were calculated with logistic regression. The predictive accuracy of an existing prediction rule for large-volume RBC transfusion was calculated for each institution.
  
  
  RESULTS
  Large-volume RBC transfusion occurred in 538 (15%) patients. When compared to the reference hospital (median crude rate), the institutional unadjusted and adjusted ORs for large-volume RBC transfusion ranged from 0.29 to 1.26 and 0.14 to 1.15, respectively (p<0.0001 for interinstitution variation). The variation was lower, but still considerable, for excessive blood loss, defined as at least 5-U RBC transfusion or reexploration; the ORs ranged from 0.42 to 1.22 (p<0.0001). The prediction rule performed well at most sites; its pooled positive predictive value for excessive blood loss was 71 percent (range, 63%-89%), and its negative predictive value was 90 percent (range, 87%-93%).
  
  
  CONCLUSIONS
  There is marked interinstitution variation in large-volume RBC transfusion in cardiac surgery that is not explained by patient- or surgery-related factors. Despite this variation, patients at high or low risk for large-volume RBC transfusion can be accurately identified by a prediction rule composed of readily available clinical variables.
authors.affiliation: University Health Network, Toronto General Hospital, Department of Anesthesia, Ontario, Canada. keyvan.karkouti@uhn.on.ca
authors.forename: Keyvan
authors.initials: K
authors.lastname: Karkouti
authors.forename: Duminda N
authors.initials: DN
authors.lastname: Wijeysundera
authors.forename: W Scott
authors.initials: WS
authors.lastname: Beattie
authors.forename: Jeannie L
authors.initials: JL
authors.lastname: Callum
authors.forename: Davy
authors.initials: D
authors.lastname: Cheng
authors.forename: Jean-Yves
authors.initials: JY
authors.lastname: Dupuis
authors.forename: Blaine
authors.initials: B
authors.lastname: Kent
authors.forename: David
authors.initials: D
authors.lastname: Mazer
authors.forename: Fraser D
authors.initials: FD
authors.lastname: Rubens
authors.forename: Corey
authors.initials: C
authors.lastname: Sawchuk
authors.forename: Terrence M
authors.initials: TM
authors.lastname: Yau
mesh_terms: D000368:Aged; D016063:Blood Loss, Surgical / Q000706:statistics & numerical data*; D006348:Cardiac Surgical Procedures / Q000379:methods*; D017707:Erythrocyte Transfusion / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D011237:Predictive Value of Tests; D012044:Regression Analysis; D015203:Reproducibility of Results; D012189:Retrospective Studies