Abstract 12189: Gender Differences in Intra-Operative Blood Transfusions: Analysis of 54,122 Coronary Artery Bypass (CABG) Procedures

Abstract

Background/Hypothesis: Women have higher morbidity and mortality associated with CABG procedures than men. The extent intra-operative red blood cell (RBC) transfusions contribute to gender differences in surgical outcomes is not established. We hypothesized that women are at increased risk for RBC transfusions due to lower pre-op hematocrit (Hct) and blood volume, but that other factors may also contribute. Methods: Consecutive, non-reoperative CABG procedures from 189 institutions (2012 -2015) were reviewed. Gender differences and odds ratios for intra-operative transfusion were evaluated with logistic regression models adjusting for age, blood volume (Nadler formula-to normalize for height and weight), procedure acuity, net extracorporeal circuit prime volume, use of retrograde autologous priming, first Hct in OR, nadir Hct on cardiopulmonary bypass (CPB), volume added on CPB, ultra-filtration volume, urine output on CPB, and procedure duration. Results: Among 54,122 patients (25.3% female), 21.9% (n=11,901) received a RBC transfusion. Compared to men, female patients were older (66 yrs vs. 64 yrs, p<.001), had lower blood volumes (4.3L vs. 5.6L, p<.001), and lower pre-op Hct (32.9% vs. 37.2%, p<.001). Transfusion rates were 3-fold higher in women vs. men (45.1% vs 13.7%, p<.001). Even after adjustment for independent predictors of intra-operative transfusion, women remained at increased risk vs men (OR = 1.3, 95% CI = 1.2 -1.4). No gender differences in transfusion rates were observed for Hct 21%-23% (Figure). Conclusions: Women have an increased risk of intra-operative RBC transfusion vs men. After adjusting for height and weight, much of this risk is due to gender differences in pre-op Hct and blood volume, however a residual significant risk remained after adjustment. Perfusion strategies aimed at gender differences may minimize unnecessary transfusions. Future study on the impact of gender on transfusion practice in cardiac surgery is warranted.