The age of red blood cells is associated with bacterial infections in critically ill trauma patients

Background. Blood transfusion increases the risk of nosocomial infection in trauma patients. Specific patient- and transfusion-related risk factors are largely unknown. In this study, risk factors for developing a bacterial infection after transfusion of red blood cells (RBC) or platelets were determined in a cohort of transfused critically ill trauma patients. Material and methods. A retrospective study was conducted in a mixed medical-surgical Intensive Care Unit (ICU) of a level-1 university trauma centre, in trauma patients who received a RBC or platelet transfusion. Patients who developed a bacterial infection after transfusion were compared to transfused controls who did not develop such an infection. Multivariable logistic regression was used to determine risk factors for infection. Results. Of the 7,118 patients admitted to the ICU during the study period, 196 trauma patients met the inclusion criteria. An infection developed in 56 patients (29%). Infection occurred irrespective of the administration of antibiotics as part of selective digestive tract decontamination, surgery status or Injury Severity Score. Transfusion of RBC stored for more than 14 days was associated with infection in trauma patients (odds ratio 1.038, [95% CI: 1.01-1.07], p=0.036). Neither the amount of RBC nor that of platelets was associated with onset of infection. Conclusions. Transfusion of RBC stored for more then 14 days is a risk factor for onset of bacterial infection after trauma, irrespective of the use of prophylactic antibiotics. Transfusion of platelets was not a risk factor. These results may contribute to designing prospective studies on transfusion of fresh RBC only in trauma patients