The effect of older blood on mortality, need for ICU care, and the length of ICU stay after major trauma.

The purpose of this study was to determine if the quantity and age of blood is an independent risk factor for in-hospital mortality, need for intensive care unit (ICU) care, and an increased length of stay in the ICU. This was a retrospective cohort study performed at a level I trauma center between 2001 and 2003. Consecutive trauma patients who received at least 1 unit of packed red blood cells (PRBCs) were included. The number of units of PRBCs transfused and the ages of each unit of PRBCs were recorded. Other variables including the patient's age, sex, Trauma-Related Injury Severity Score (TRISS), and whether the blood was leukopoor were collected. End points included in-hospital mortality, need for ICU care, and the length of stay in the ICU (in days). Multivariable logistic and Poisson regression analyses were performed to model the independent effect of the dose of aged blood (defined as the product of the average age of all units received and the total number of units received) with respect to each end point while controlling for age, TRISS, the total number of units administered, and the proportion of blood that was leukopoor. During the study period, 275 patients were studied. Patients who received older blood had a significantly longer ICU stay (RR 1.15, 95% CI: 1.11-1.20), possibly reflecting a higher level of organ dysfunction. Patients who received older blood, however, did not have a significantly higher in-hospital mortality rate (OR 1.21, 95% CI: 0.87-1.69) or a significantly higher need for ICU care (OR 1.20, 95% CI: 0.87-1.64). The quantity of aged blood is an independent risk factor for length of ICU care. This may be a proxy indicator for multiple organ failure. Further research is required to define which patients may benefit from newer blood.