[The ABLE study: A randomized controlled trial on the efficacy of fresh red cell units to improve the outcome of transfused critically ill adults]

Red blood cell units are stored up to 42 days post-collection. The standard policy of blood banks is to deliver the oldest units in order to limit blood wastage. Many caregivers believe that giving fresh rather than old units can improve the outcome of their transfused patients. The ABLE study aims to check if the transfusion of red blood cell units stored seven days or less (fresh arm) improve the outcome of transfused critically ill adults compared to patients who received units delivered according to the standard delivery policy (control arm). From March 2009 to May 2014, 1211 patients were allocated to the fresh arm, 1219 to the control arm (length of storage: 6.1 ± 4.9 and 22.0 ± 8.4 days respectively, P<0.001). The primary outcome measure was 90-day all-cause mortality post-randomisation: there were 448 deaths (37.0%) in the fresh arm and 430 (35.3%) in the control arm (absolute risk difference: 1.7%; 95% confidence interval: -2.1% to 5.5%). In a survival analysis, the risk of death was higher in the fresh arm (hazard ratio: 1.1; 95%CI: 0.9 to 1.2), but the difference was not statistically significant (P=0.38). The same trend against the fresh arm was observed with all but one secondary outcome measures. The conclusion is that the transfusion of red blood cell units stored seven days or less does not improve the outcome of critically ill adults compared to the transfusion of units stored about three weeks (22.0 ± 8.4 days).