Preoperative anaemia linked to adverse outcomes following cardiac surgery

Researchers have found preoperative anaemia to be independently associated with adverse outcomes following cardiac surgery. Preoperative anaemia is the single most important determinant of perioperative red blood cell transfusion in heart surgery. More recently, evidence has suggested that preoperative anaemia may also be an independent risk factor for short- and long-term morbidity and mortality among patients with coronary artery disease, congestive heart failure and cardiac surgery. Karkouti and co-workers conducted a multicentre, retrospective cohort study to further examine the relationship between preoperative anaemia and outcomes following cardiac surgery. The authors note that to date, “the prognostic value of anaemia has been studied primarily in non-operative settings, where it has been shown to be an important risk factor for short- and long-term outcomes...” Data were collected for 3,500 consecutive patients who underwent cardiac surgery. The primary dependent variable was the composite outcome of in-hospital death, stroke, or acute kidney injury was obtained. The overall prevalence of preoperative anaemia (haemoglobin <12.5 g/dL) was found to be 26%, and that this condition was independently associated with adverse outcomes. This was reflected in the unadjusted odds ratio for the composite outcome in anaemic versus non-anaemic patients being 3.6 (p<0.0001). After controlling for confounding patient-specific and surgical variables by multivariable logistic regression modelling, preoperative anaemia was independently associated with the composite adverse outcome as reflected by an odds ratio of 2.0 (p<0.0001). In addition, propensity score-based matching — which was used to obtain unbiased estimates by matching anaemic with non-anaemic patients — revealed an odds ratio for the composite adverse outcome of 1.8 (p=0.005). The authors concluded that preoperative anaemia is an important risk factor for adverse outcome compared with non-anaemic patients, and importantly, this relationship appears to be independent of the effects of red blood cell transfusion. Future studies should examine whether treating preoperative anaemia can improve perioperative outcomes among patients undergoing cardiac surgery, they added. Reference...