Does the severity of preoperative anemia or blood transfusion have a stronger impact on long-term survival after cardiac surgery?

Background: Preoperative anemia and transfusion are associated with increased morbidity and mortality in cardiac surgery patients. It is unclear which of these factors plays the leading role in poor outcomes after cardiac surgery. The goal of this study was to analyze the influence of anemias of varying severity and intraoperative transfusion on long-term survival, and to characterize their interaction in cardiac surgery patients. Methods: This was an observational cohort study conducted at a German university hospital. All patients undergoing cardiac surgery between 2006 and 2011 were screened for eligibility; duration of follow-up was 3 years. A total of 4494 patients were suitable for analysis; data on long-term survival were available for 3131 of these patients. The main outcome measure was survival at the 3-year follow-up. Length of stay and in-hospital mortality were assessed as secondary outcomes. Results: Multivariate Cox regression analyses indicated that both the severity of preoperative anemia (mild anemia: hazard ratio [HR], 1.441; 95% confidence interval [CI], 1.201-1.728; severe anemia: HR, 1.805; 95% CI, 1.336-2.440) and intraoperative transfusion (HR, 1.340; 95% CI, 1.109-1.620) were associated with decreased long-term survival. Long-term survival was worse in anemic patients who received an intraoperative transfusion compared with those who did not receive an intraoperative transfusion. Conclusions: Both preoperative anemia and transfusion are by themselves and in combination associated with decreased long-term survival. When anemic patients require transfusion, our results provide evidence that the risk of death after cardiac surgery may depend to a considerable extent on the severity of preoperative anemia.