Clinical impact of red cell storage duration: an individual patient data meta-analysis

• In an individual patient data meta analysis (n=33,549) there was no survival benefit from transfusing fresher compared to older RBC units • Findings support current blood inventory management policies and are applicable to most hospitalized adults Randomized trials reported no benefit from transfusion of red blood cell (RBC) units stored for shorter durations compared to standard care. However, there was insufficient evidence to exclude harms at extremes of storage age or explore subgroup differences. We therefore performed an individual patient data meta-analysis to determine the effect of fresher vs. older RBC transfusion on 28-day mortality in hospitalized adults. Individual patient data was sought from clinical trials that randomized more than 1000 adult patients. For the meta-analysis, we used a logistic regression model with a trial-specific fixed effect. Four studies provided individual data from 33,549 patients enrolled from March 2009 through December 2016 from 12 countries. After exclusions, 32,959 (98.2%) patients were included in the analysis. Patients received a median (IQR) of 2 (1 – 4) RBC units with a storage duration of 10 (7 – 15) days in the fresh and 23 (16 – 30) days in the older group. Death occurred in 1,446 of 12,236 patients (11.8%) in the fresher and 1,984 of 20,572 patients (9.6%) in the older group (odds ratio 1.06; 95% CI 0.98 to 1.14; p =0.124). No significant subgroup differences were identified. We found an association between receiving one and two or more RBCs ≤7 days and higher mortality (odds ratio 1.18, 95%CI 1.02 to 1.35; p =0.024 and 1.17, 95% CI 1.04 to 1.32; p =0.015, respectively), but not with any RBC ≥35 days. Adjusted analyses confirmed these findings. Our findings support current blood inventory management policies and are applicable to most hospitalized adults. ClinicalTrials.gov: NCT05482737