Abstract 3912: Blood Transfusions Are Associated with Worse Outcomes Compared to No Transfusion in Patients with Similar Degrees of Anemia and Hematocrit Decline While Undergoing Coronary Angiography
Introduction: Blood transfusions are common in anemic patients with coronary artery disease (CAD), and the increased mortality associated with transfusion is well recognized. Whether the transfusion itself is responsible for increased risk beyond that of the underlying cause of anemia is controversial.
Methods: Patients who underwent coronary angiography and received a transfusion of red blood cells were studied. Transfused patients (n=728) were matched to non-transfused controls (n=728) by age (±5 years), sex, baseline hematocrit (±2 points), and drop in hematocrit (±2 points) to control for the effects of underlying causes of anemia. Additionally, logistic regression was used to evaluate whether transfusion with dissimilar (but compatible) ABO/Rh blood predicted in-hospital, 6-month, and 1-year death.
Results: Age averaged 66.7±13.0 years and 54.4% were male. Baseline hematocrit was <30 in 14% of the patients. Transfused patients had an increased risk of in-hospital (adjusted OR=7.30, p<0.0001), 6 month (adjusted OR=1.82, p<0.001), and 1-year death (adjusted OR=1.72, p=0.002) compared to matched controls with similar declines in hematocrit. Transfusion with dissimilar (compatible) blood types occurred in 111 patients. Also, in univariate analysis, transfusion by dissimilar versus perfectly matched ABO donors predicted increased in-hospital, 6 month, and 1 year death: Odds Ratio [OR]= 2.55, p=0.01; OR=2.50, p=0.009; OR=2.77, p=0.003, respectively. In multivariate analysis, 1-year death remained significant (OR=2.10, p=0.05); in-hospital (OR=1.77, p=0.18) and 6-month death (OR=1.70, p=0.17) were still predictors of risk although significance was not retained.
Conclusions: When compared to non-transfused patients undergoing coronary angiography with similar baseline and decreased hematocrits, transfused patients were at increased risk of in-hospital, 6-month, and 1-year death. Furthermore, receiving ABO/Rh dissimilar blood was associated with a two-fold increase in mortality at one year. These results cast doubt on the practice of routinely transfusing blood in CAD patients without severe anemia.