Introduction: Red blood cell (RBC) transfusions are frequent in cardiac surgery and are associated with higher morbidity, mortality, prolonged hospitalization, and increased healthcare costs. Several patient- and procedure-related factors have been identified as transfusion predictors. Studying these predictors in specific populations allows more accurate risk stratification and tailored clinical decision-making. RBC transfusions represent a significant economic burden for healthcare systems due to increased resource utilization and hospital costs overall. The aim of this study was to identify independent risk factors of RBC transfusion, evaluate its economic impact, and estimate potential cost savings from eliminating preoperative anemia.

Methods: We conducted a retrospective cohort study at a tertiary hospital in Portugal, including 661 adults who underwent elective cardiac surgery between April 2020 and April 2021. The primary outcome was the need for at least one RBC transfusion during hospitalization. Secondary outcomes included 30-day mortality, infection, acute kidney injury, prolonged mechanical ventilation, intensive care unit stay, hospital length of stay (LOS), and hospital costs. Independent risk factors were identified using multivariable logistic regression. An economic analysis compared costs between transfused and non-transfused patients. To estimate potential cost reductions, a simulation model was developed assuming the elimination of preoperative anemia and applying the observed transfusion patterns of non-anemic patients to the entire cohort.

Results: Red blood cell transfusion occurred in 41.3% of patients. The identified predictors were preoperative anemia (OR 3.67; 2.00 – 6.74), female sex (OR 2.06; 1.22 – 3.48), higher EuroSCORE II (OR 1.15; 1.03 – 1.29), longer cardiopulmonary bypass time (OR 1.01; 1.00 – 1.02) and lower intraoperative nadir hemoglobin (OR 0.48; 0.40 – 0.58), after adjusting for postoperative hemorrhage. Transfused patients had longer hospital stays (median 10 vs 8 days) and higher costs (median increase of €2264.44). After adjustment for infection and prolonged ventilation, transfusion was no longer independently associated with LOS. Eliminating preoperative anemia could prevent 47 transfusions, reduce 94 hospital days, and save €106 429 over 13 months overall.

Conclusion: Red blood cell transfusion was associated with longer hospital stays, likely due to higher infection rates and prolonged mechanical ventilation. Correcting preoperative anemia could potentially reduce transfusion rates and related hospital costs in cardiac surgery.