title: The independent association of massive blood loss with mortality in cardiac surgery.
abstract: BACKGROUND
  Although the association between massive perioperative blood loss (MBL) and adverse outcomes is well recognized, it is unclear whether MBL is an independent risk factor or, instead, simply a marker for other adverse events or severity of illness. The objective of this cohort study was to quantify the independent association of MBL in cardiac surgery with all-cause in-hospital mortality.
  
  
  METHODS
  Data were prospectively collected on consecutive patients who underwent cardiac surgery with cardiopulmonary bypass at a quaternary-care academic center from 1999 to 2003. The number of red blood cell (RBC) units transfused within 1 day of surgery was used as a surrogate measure of perioperative blood loss. Receiver-operating characteristic curve analyses were employed to identify the most appropriate cutoff for defining MBL. The independent association of MBL with mortality was determined with multivariable logistic regression analyses. Bootstrapping and sensitivity analyses were used to confirm the validity of the results.
  
  
  RESULTS
  MBL was defined as receiving at least 5 units of RBCs within 1 day of surgery. Of 9215 patients analyzed, 1.8 percent (n = 169) died and 9.7 percent (n = 890) had MBL. After adjusting for multiple potential confounders (including perioperative adverse events), MBL was associated with an 8.1-fold (95% confidence interval, 3.9-17.0) increase in the odds of death. This risk estimate was stable across different modeling conditions as well as in bootstrap sampling.
  
  
  CONCLUSIONS
  MBL after cardiac surgery has a strong, independent association with in-hospital mortality.
authors.affiliation: Department of Anesthesia, University of Toronto, Toronto, 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: Terrence M
authors.initials: TM
authors.lastname: Yau
authors.forename: W Scott
authors.initials: WS
authors.lastname: Beattie
authors.forename: Esamelden
authors.initials: E
authors.lastname: Abdelnaem
authors.forename: Stuart A
authors.initials: SA
authors.lastname: McCluskey
authors.forename: Mohammed
authors.initials: M
authors.lastname: Ghannam
authors.forename: Eric
authors.initials: E
authors.lastname: Yeo
authors.forename: George
authors.initials: G
authors.lastname: Djaiani
authors.forename: Jacek
authors.initials: J
authors.lastname: Karski
mesh_terms: D000368:Aged; D016063:Blood Loss, Surgical / Q000401:mortality*; D006348:Cardiac Surgical Procedures / Q000401:mortality*; D002315:Cardiopulmonary Bypass / Q000401:mortality; D002423:Cause of Death; D015331:Cohort Studies; D017707:Erythrocyte Transfusion / Q000706:statistics & numerical data; D005260:Female; D017052:Hospital Mortality; D006801:Humans; D008297:Male; D008875:Middle Aged; D015233:Models, Statistical; D015399:Nursing Research; D011446:Prospective Studies; D012372:ROC Curve; D012307:Risk Factors