Objective: Red blood cell transfusion (RBCT) is commonly prescribed to critically ill patients with anemia. Nevertheless, the benefits of RBCT in these patients, particularly critically ill surgical patients, are still controversial. The aim of this study is to explore the association between RBCT and hospital mortality in Thai critically ill surgical patients.
Material and Method: This study was a part of the multi-center, prospective, observational study, which included adult patients admitted to the SICUs after surgery. Patients were categorized into transfusion and no transfusion groups according to whether they received RBCT during SICU stay or not. The multiple logistic regression analysis was performed to determine whether RBCT was an independent risk factor for hospital mortality. The patients were also matched between two groups based on the propensity score for RBCT requirement and were then compared.
Results: There were 2,531 patients included in this study. The incidence of RBCT in SICU was 40.3%. Overall, there was no association between RBCT in SICU and hospital mortality (adjusted OR 1.33, 95% CI 0.83-2.11) except in the subgroup of patients with age of <65 years old (adjusted OR 1.99, 95% CI 1.03-3.84). However, when the amount of RBCT was more than 1,200 mL, it was independently associated with increased hospital mortality (adjusted OR 2.55, 95% CI 1.35-4.81). In the propensity-score matching cohort, there was no association between RBCT in SICU and hospital mortality (adjusted OR 1.56, 95% CI 0.88-2.77) except when the amount of RBCT was more than 600 mL (601-1,200 mL, adjusted OR 3.14, 95% CI 1.47-6.72 and >1,200 mL, adjusted OR 3.58, 95% CI 1.36-9.48).
Conclusion: RBCT should be considered as a life-saving intervention but with potential risks of adverse events. Identifying patients who will likely gain benefit from RBCT and implementing the restrictive transfusion strategy may be the keys to improve outcomes.

Keywords: Blood transfusion, Critical care, Mortality, Outcomes, Surgical patients