Association Between Anemia and Blood Transfusion With Long-term Mortality After Cardiac Surgery

Background: Preoperative anemia and red blood cell (RBC) transfusion are both associated with in-hospital mortality after cardiac surgery. The aim of this study was to investigate the interactions between preoperative anemia and RBC transfusion and their effect on the long-term survival of patients undergoing cardiac surgery. Methods: Between 2005 and 2012, 1170 patients with anemia who underwent elective or urgent cardiac surgery were included. A matched group of 1170 nonanemic patients was used as a control group. A binary logistic regression model was used. Results: The median follow-up period was 64 months (range, 0-127). Anemic patients had higher mortality (45%, n = 526) than nonanemic patients (32%, n = 374; P <.001). Preoperative anemia was independently associated with long-term mortality (odds ratio [OR], 1.70; 95% confidence interval [CI], 1.46-2.1; P <.001), with both moderate (OR, 2.27; 95% CI, 1.72-2.99; P <.001) and mild anemia (OR, 1.39; 95% CI, 1.13-1.71; P =.002) contributing significantly. RBC transfusion was not associated with long-term mortality (OR, 1.07; 95% CI, 0.88-1.31; P =.49). There was no interaction between preoperative anemia and RBC transfusion (P =.947). Conclusions: Long-term mortality is significantly high in patients who are anemic, regardless of their transfusion status. Preoperative anemia is a strong, independent predictor of mortality and therefore should be managed before cardiac surgery.