Influence of anaemia and red blood cell transfusion on mortality in high cardiac risk patients undergoing major non-cardiac surgery: A retrospective cohort study

Abstract

Background. Perioperative anaemia is common. Physicians believe that patients at increased cardiac risk do not tolerate anaemia and, consequently, these patients receive transfusions earlier and more often. This practice runs counter to a growing body of evidence that perioperative red blood cell (RBC) transfusion is harmful. The aims of this study were as follows: (i) to assess the effects of transfusion at moderate to severely low ranges of postoperative haemoglobin concentrations; and (ii) to assess whether transfusion was beneficial in patients at high cardiac risk within these haemoglobin ranges. Methods. A single-centre retrospective cohort study enrolled 75 719 consecutive major, non-cardiac surgery patients. Multivariable logistic regressions with 98.4% confidence intervals looking at specific nadir postoperative haemoglobin groups were compared to examine the effects of anaemia, RBC transfusion, and cardiac risk on postoperative 30 day in-hospital mortality. Results. Patients at moderate to high cardiac risk had a two-fold greater prevalence of preoperative anaemia. In unadjusted analysis, RBC transfusion was associated with increased mortality at all transfusion thresholds in all patients. After adjustment, RBC transfusion in patients with high cardiac risk was associated with decreased mortality when the postoperative haemoglobin concentration was <80 g litre-1 [odds ratio 0.37 (98.4% confidence interval 0.17-0.77)]. Conclusions. High cardiac risk was associated with increased incidence of anaemia, transfusion, and mortality. Red blood cell transfusion is associated with reduced mortality only in high cardiac risk patients with nadir postoperative haemoglobin concentration <80 g litre-1. Transfusion, the main treatment for postoperative anaemia, does not appear to be associated with reduced postoperative mortality at higher nadir haemoglobin ranges.