The Restrictive Red Blood Cell Transfusion Strategy for Critically Injured Patients (RESTRIC) trial: a cluster-randomized, crossover, non-inferiority multicenter trial of restrictive transfusion in trauma

BACKGROUND: The efficacies of fresh frozen plasma and coagulation factor transfusion have been widely evaluated in trauma-induced coagulopathy management during the acute post-injury phase. However, the efficacy of red blood cell transfusion has not been adequately investigated in patients with severe trauma, and the optimal hemoglobin target level during the acute post-injury and resuscitation phases remains unclear. Therefore, this study aimed to examine whether a restrictive transfusion strategy was clinically non-inferior to a liberal transfusion strategy during the acute post-injury phase. METHODS: This cluster-randomized, crossover, non-inferiority multicenter trial was conducted at 22 tertiary emergency medical institutions in Japan and included adult patients with severe trauma at risk of major bleeding. The institutions were allocated a restrictive or liberal transfusion strategy (target hemoglobin levels: 7–9 or 10–12 g/dL, respectively). The strategies were applied to patients immediately after arrival at the emergency department. The primary outcome was 28-day survival after arrival at the emergency department. Secondary outcomes included transfusion volume, complication rates, and event-free days. The non-inferiority margin was set at 3%. RESULTS: The 28-day survival rates of patients in the restrictive (n = 216) and liberal (n = 195) strategy groups were 92.1% and 91.3%, respectively. The adjusted odds ratio for 28-day survival in the restrictive versus liberal strategy group was 1.02 (95% confidence interval: 0.49–2.13). Significant non-inferiority was not observed. Transfusion volumes and hemoglobin levels were lower in the restrictive strategy group than in the liberal strategy group. No between-group differences were noted in complication rates or event-free days. CONCLUSIONS: Although non-inferiority of the restrictive versus liberal transfusion strategy for 28-day survival was not statistically significant, the mortality and complication rates were similar between the groups. The restrictive transfusion strategy results in a lower transfusion volume. Trial registration number: umin.ac.jp/ctr: UMIN000034405, registration date: 8 October 2018. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s40560-023-00682-3.