In cardiac surgery, women have higher short-term mortality and a higher risk of receiving red blood cell (RBC) transfusions than men. This study's aim was to evaluate possible sex differences in RBC transfusions in cardiac surgery and their association with preoperative hemoglobin levels, body mass index, and 30-day mortality. A single-center retrospective study was conducted with 1583 patients (1181 men and 402 women) undergoing cardiac surgery. A total of 64.4% of the women and 33.0% of the men received an RBC transfusion. In a multivariable analysis, female sex was an independent predictor of RBC transfusion (OR 3.88, 95% CI 2.95-5.11, p < 0.001). Other independent predictors of RBC transfusion were age, preoperative hemoglobin level, and body mass index. The women were more likely to receive RBC transfusions than the men, regardless of the type of cardiac surgery. Decreased transfusion risk was found in all higher-than-normal weight categories in the women, but only in the severe obesity category in the men. Preoperative hemoglobin was similarly associated with RBC transfusion in the men and women. The crude 30-day mortality rate was higher in the women than in the men (2.5% vs. 0.9%, p = 0.018). In both sexes, RBC transfusion was associated with an increased probability of death within 30 days.
Keywords: 30-day mortality; body mass index; cardiac surgery; preoperative hemoglobin; red blood cell transfusion; sex difference.