Effectiveness of Blood Transfusions and Predictors of Response in Critically ill Patients

Introduction: Blood transfusions are commonly used in critically ill patients. However, hemoglobin response to such transfusions is variable and has not been well characterized. We aimed to evaluate the hemoglobin changes after packed red blood cell (pRBC) transfusions and identify predictors of response in critically ill patients.


Methods: This retrospective cohort study used the e-ICU Collaborative Research database, a multi-center dataset from over 200 hospitals. We included adult critically ill patients who received pRBC transfusions and had hemoglobin measured within 12 hours before and after transfusion. Patients with documented bleeding were excluded. Hemoglobin increase per unit of pRBC was evaluated. In addition, factors associated with response were assessed by classifying patients as responders (≥1 g/dL increase) and non-responders ( < 1 g/dL increase). Descriptive statistics were used to summarize the data, and regression analyses were used to identify factors associated with hemoglobin response.


Results: A total of 8,022 critically ill patients received blood transfusions and met the inclusion criteria. The mean age was 62 ±17(SD) years, and 4,194 (52.3%) were males. The most common ICU admission diagnoses were cardiovascular (n= 2,225; 27.7%) and respiratory (n= 1,725; 21.5%). The mean increase in hemoglobin per unit of pRBC transfused was 1.4 ± 1.5(SD) g/dL. Among patients in the responder’s group, the mean increase in hemoglobin per unit of pRBC was 2.3 ±1.2(SD) g/dL, while for patients in the non-responder’s group, the mean increase was 0.1 ± 0.8(SD) g/dL (p < 0.001). Among responders, a greater proportion were females (52.7% vs. 40.4%, p< 0.001) and had lower mean body weight (87 ±24.6 vs. 79 ±27.2 kg, p< 0.001). Patients in the responders group also had lower baseline hemoglobin (7.1 ± 1.0 vs. 8.2 ± 1.5g/dL, p< 0.001). In logistic regression, a hemoglobin response of ≥1 g/dL was significantly associated with female gender (OR: 1.62; 95%CI 1.50-1.79), and lower baseline hemoglobin (OR: 3.75; 95%CI: 3.43-4.10).


Conclusions: Among a large cohort of critically ill patients, blood transfusions were associated with a mean hemoglobin increase of 1.4 g/dL but the response was variable among patients. Female gender and lower baseline hemoglobin were associated with greater response.