The additive effects of anaemia and transfusion on long-term survival after coronary artery bypass surgery

OBJECTIVES: To compare the independent and combined effects of anaemia and red blood cell transfusion on late survival after isolated coronary artery bypass grafting. METHODS: Retrospective analysis of 5243 consecutive patients undergoing primary isolated coronary artery bypass grafting, performed from 2000 to 2015, in a Portuguese Academic Hospital. We identified 1649 patients with preoperative anaemia (A(+)) and 1422 patients who received a perioperative transfusion (T+)-the 4 possible combinations allowed for the creation of 4 subgroups (A(-)/T-, A(-)/T+, A(+)/T- and A(+)/T+). The primary endpoint was all-cause mortality at 10 years. We employed inverse probability weighting to control for confounding variables. RESULTS: Thirty-one percent of the patients had preoperative anaemia, and 27.0% had at least one packed red blood cell transfusion. Inverse probability weighting was effective in eliminating differences in all significant baseline characteristics. The primary endpoint of all-cause mortality at 10 years occurred in 568 patients (20.5%) in the A(-)/T- group, as compared with 204 (24.4%) in the A(-)/T+ group (hazard ratio, 1.14; 95% confidence interval, 1.00 to 1.31; P = 0.053), 358 (33.8%) in the A(+)/T- group (hazard ratio, 1.53; 95% confidence interval, 1.38 to 1.71; P < 0.001), 254 (43.6%) in the A(+)/T+ group (hazard ratio, 2.25; 95% confidence interval, 1.97 to 2.56; P < 0.001). CONCLUSIONS: This longitudinal, population-level study emphasizes the adverse long-term outcomes of preoperative anaemia and perioperative red blood cell transfusion. It stresses the importance of an evidence-based, multimodal and multidisciplinary approach to conserving blood resources and optimizing outcomes in patients at high risk for transfusion.