Anemia and blood transfusion in a surgical intensive care unit

INTRODUCTION Studies in intensive care unit (ICU) patients have suggested that anemia and blood transfusions can influence outcomes, but these effects have not been widely investigated specifically in surgical ICU patients. METHODS We retrospectively analyzed the prospectively collected data from all adult patients (>18 years old) admitted to a 50-bed surgical ICU between 1st March 2004 and 30th July 2006. RESULTS Of the 5925 patients admitted during the study period, 1833 (30.9%) received a blood transfusion in the ICU. Hemoglobin concentrations were < 9 g/dl on at least one occasion in 57.6% of patients. Lower hemoglobin concentrations were associated with a higher Simplified Acute Physiology Score II and Sequential Organ Failure Assessment score, greater mortality rates, and longer ICU and hospital lengths of stay. Transfused patients had higher ICU (12.5 vs. 3.2%) and hospital (18.3 vs. 6.5%) mortality rates (both p < 0.001) than non-transfused patients. However, ICU and in-hospital mortality rates were similar among transfused and non-transfused matched pairs according to a propensity score (n = 1184 pairs), and after adjustment for possible confounders in a multivariable analysis, higher hemoglobin concentrations (RR 0.97[0.95-0.98], per 1 g/dl, p < 0.001) and blood transfusions (RR 0.96[0.92-0.99], p = 0.031) were independently associated with a lower risk of in-hospital death, especially in patients aged from 66 to 80 years, in patients admitted to the ICU after non-cardiovascular surgery, in patients with higher severity scores, and in patients with severe sepsis. CONCLUSIONS In this group of surgical ICU patients, anemia was common and was associated with higher morbidity and mortality. Higher hemoglobin concentrations and receipt of a blood transfusion were independently associated with a lower risk of in-hospital death. Randomized control studies are warranted to confirm the potential benefit of blood transfusions in these subpopulations.