The effects of iron deficiency on red blood cell transfusion requirements in non-bleeding critically ill patients

Introduction: Critically ill patients often need blood transfusion, but no reliable predictors of transfusion requirements are available at Intensive Care Unit (ICU) admission. We hypothesized that ICU patients admitted with Iron Deficiency (ID) may be at higher risk for developing anemia, requiring blood transfusion. The aims of this study were to determine the frequency of ID in ICU patients admission and to investigate its relationship with transfusion requirements in ICU patients. Methods: Two hundred ninety-six patients admitted to the general ICU were enrolled in the prospective observational study. We studied 268 patients, after excluding those transfused on or before ICU admission. The patients recorded age, gender, diagnosis, severity scores, presence of sepsis, ICU complications, ICU treatments, and transfusion-free interval. ID was assessed on the basis of several parameters, including hemoglobin, hematocrit, levels of serum iron, transferrin saturation, levels of ferritin, soluble transferrin receptor, C-reactive protein. Results: The mean age was 48 years. Of 268 patients (138 male/ 130 female), 114 (42.8%) had ID with outcomes of blood samples were used at ICU admission. The overall transfusion rate was 38.8%, being higher in ID patients than in normal iron profile patients (40.3 vs. 18.9%, P=0.001). After adjusting for severity of illness and hemoglobin level, ID patients remained significantly associated with transfusion, with a hazard ratio of 5.3 (95% CI, 1.8-14.8; P=0.001). Conclusion: ID is common at ICU admission and is associated with higher transfusion requirements. These findings have important implications for transfusion practices for in ICU patients.