title: Is single-unit blood transfusion bad post-coronary artery bypass surgery?
abstract: OBJECTIVE
  Publications in the surgical literature are very consistent in their conclusions that blood is dangerous with regard to in-hospital mortality, morbidity and long-term survival. Blood is frequently used as a volume expander while simultaneously increasing the haematocrit. We investigated the effects of a single-unit blood transfusion on long-term survival post-cardiac surgery in isolated coronary artery bypass grafting patients.
  
  
  METHODS
  A prospective single-institution cardiac surgery database was analysed involving 4615 patients. Univariate, multivariate stepwise Cox regression analysis and propensity matching were performed to identify whether a single-unit blood transfusion was detrimental to long-term survival.
  
  
  RESULTS
  Univariate analysis revealed that blood was significantly associated with a reduced long-term survival even with a single-unit transfused, P = 0.0001. Cox multivariate regression analysis identified age, ejection fraction, preoperative dialysis, logistic EuroSCORE, postoperative CKMB, blood transfusion, urgent operative status and atrial fibrillation as significant factors determining long-term survival. When the Cox regression was repeated with patients who received no blood or only one unit of blood, transfusion was not a risk factor for long-term survival. An interaction analysis revealed that blood transfusion was significantly interacting with preoperative haemoglobin levels, P = 0.02. Propensity analysis demonstrated that a single-unit transfusion is not associated with a detrimental long-term survival, P = 0.3.
  
  
  CONCLUSIONS
  Cox regression and propensity matching both indicate that a single-unit transfusion is not a significant cause of reduced long-term survival. Preoperative anaemia is a significant confounding factor. Despite demonstrating the negligible risks of a single-unit blood transfusion, we are not advocating liberal transfusion and would recommend changing from a double-unit to a single-unit transfusion policy. We speculate that blood is not bad, but that the underlying reason that it is given might be.
authors: Department of Cardiac Surgery, Liverpool Heart and Chest Hospital, Liverpool, UK.
authors: Richard
authors: R
authors: Warwick
authors: Neeraj
authors: N
authors: Mediratta
authors: John
authors: J
authors: Chalmers
authors: Mark
authors: M
authors: Pullan
authors: Matthew
authors: M
authors: Shaw
authors: James
authors: J
authors: McShane
authors: Michael
authors: M
authors: Poullis
mesh_terms: D000368:Aged; D000740:Anemia / Q000097:blood / Q000150:complications / Q000401:mortality / Q000628:therapy; D015415:Biomarkers / Q000097:blood; D001803:Blood Transfusion / Q000401:mortality; D001026:Coronary Artery Bypass / Q000009:adverse effects* / Q000401:mortality; D004739:England; D005260:Female; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D057216:Propensity Score; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D065227:Transfusion Reaction; D016896:Treatment Outcome
chemical_list: D015415:Biomarkers; D006454:Hemoglobins
keywords: Blood transfusion; Coronary; Survival