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

Abstract

Abstract Objectives To compare the independent and combined effects of anaemia and red blood cell transfusion on late survival after isolated coronary artery bypass grafting (CABG). Methods Retrospective analysis of 5243 consecutive patients undergoing primary isolated CABG, 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 four possible combinations allowed for the creation of four subgroups (A-/T-, A-/T+, A+/T-, and A+/T+). The primary endpoint was all-cause mortality at ten 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 ten years occurred in 568 patients (20.5%) in the A-/T- group, as compared with 204 (24.4%) in the A-/T+ group (HR, 1.14; 95% CI, 1.00 to 1.31; p = 0.053), 358 (33.8%) in the A+/T- group (HR, 1.53; 95% CI, 1.38 to 1.71; p < 0.001), 254 (43.6%) in the A+/T+ group (HR, 2.25; 95% CI, 1.97 to 2.56; p < 0.001). Conclusions This longitudinal, population-level study emphasises the adverse long-term outcomes of preoperative anaemia and perioperative RBC transfusion. It stresses the importance of an evidence-based, multimodal, and multidisciplinary approach to conserving blood resources and optimising outcomes in patients at high risk for transfusion.