A pilot feasibility trial of allocation of freshest available red blood cells versus standard care in critically ill patients

BACKGROUND: Prolonged storage of red blood cells (RBCs) may increase posttransfusion adverse events in critically ill patients. We aimed to evaluate in intensive care unit (ICU) patients 1) the feasibility of allocating freshest available compatible RBCs versus standard care and 2) the suitability of this approach in the design of a large randomized controlled trial (RCT). STUDY DESIGN AND METHODS: Eligible patients from two adult ICUs were randomly assigned to receive either the freshest available compatible RBCs or the standard care (the oldest compatible available RBCs) for all transfusions during their ICU stay. Study group allocation was concealed from patients and bedside clinicians, but the transfusion service was unblinded. The study endpoints were the feasibility of the study procedures, including success of the ICU Web randomization, the ICU staff blinding, and the correct delivery of the RBC units by the transfusion service in accordance with the allocated study group. In addition, we measured the difference in age of RBC units between the two groups. RESULTS: During a 3-month period, 177 RBC units were delivered to 51 patients. All study procedures, including randomization, blinding, and delivery of blood in accordance with the study group were successful. The mean (+/- SD) of the mean age of the RBC received by each patient was lower in the fresher blood group compared with the standard care group (12.1 [+/- 3.8] days vs. 23 [+/- 8.4] days; p < 0.001). CONCLUSION: Randomized delivery of the freshest available RBCs versus standard care to ICU patients who were prescribed transfusion for clinical reasons is feasible, with a clinically relevant degree of storage duration separation achievable between the two study groups. These findings support the feasibility of a future large pragmatic RCT.