Age of red blood cells is not associated with in-hospital mortality in massively transfused patients

BACKGROUND: Studies comparing mortality following massive transfusion (MT) with fresher versus longer-stored red blood cells (RBCs) have focused on trauma patients. The Australian and New Zealand Massive Transfusion Registry collects data on all adult MT cases (≥5 RBCs within 4 hours, any bleeding context, ≥18 years) at participating hospitals. METHODS: Years 2007 to 2018 data from 29 hospitals were analyzed to quantify the association between mortality and RBC storage time in adult MT cases. We ran three logistic regression models separately on each of seven bleeding contexts, with in-hospital mortality as the outcome and, in turn, (1) mean storage time (STmean) quartiles, (2) proportion of RBCs ≥30 days old (propOLD), and (3) scalar age of blood index as predictors. RESULTS: A total of 8,685 adult MT cases involving transfusion of 126,622 RBCs were analyzed with Australian and New Zealand data analyzed separately. Mean storage times for these cases were (by quartile in ascending order) as follows: Australia, 12.5 days (range, 3.1-15.5 days), 17.7 (15.5-19.9), 22.3 (19.9-24.9), and 29.8 (24.9-41.7); New Zealand, 11.3 days (3.6-13.7), 15.3 (13.7-16.8), 18.7 (16.8-20.7), and 24.5 (20.7-35.6). The odds ratios comparing in-hospital mortality for each quartile with that of the control first quartile (freshest blood), proportion of longer-stored (≥30 days) RBCs, and scalar age of blood index were not statistically significant across all bleeding contexts. CONCLUSION: We find no correlation between in-hospital mortality and storage time of transfused RBCs in a large cohort of adult MT patients representing all bleeding contexts. These results are consistent with those of recent large multicenter trials. LEVEL OF EVIDENCE: Epidemiologic, level III; Therapeutic, level IV.