Restrictive vs Liberal Transfusion Strategy in Traumatic Brain Injury: A Secondary Analysis of the TRAIN Trial.

Importance: Anemia is a prevalent condition among patients with traumatic brain injury (TBI); however, the optimal hemoglobin (Hb) threshold to initiate red blood cell transfusion (RBCT) is not well defined. Objective: To assess which of 2 different Hb thresholds for guiding RBCT in patients with anemia and TBI is associated with a more favorable neurological outcome. Design, Setting, and Participants: This was a preplanned secondary analysis of the Transfusion Strategies in Acute Brain Injured Patients multicentric randomized clinical trial, conducted in 72 intensive care units across 22 countries between September 1, 2017, and December 31, 2022. Follow-up was completed June 30, 2023. Only patients with TBI were included in the present analysis, conducted from February to May 2025. Interventions: Liberal (transfusion at Hb <9 g/dL [to convert to g/L, multiply by 10.0]) vs restrictive (transfusion at Hb <7 g/dL) RBCT strategy over a maximum of 28 days. Main Outcome and Measures: The primary outcome was the occurrence of unfavorable neurological outcome, defined as a Glasgow Outcome Scale Extended score of 1 to 5 (overall range, 1-8, with higher scores indicating more favorable outcome) at 180 days. In addition, 14 prespecified serious adverse events, including infection and cerebral ischemia, were assessed. Data were analyzed using both the intention-to-treat and per-protocol principles. Results: Of 486 patients who presented with TBI (mean [SD] age, 46.8 [17.6] years; 347 [71.4%] male), 475 were included in the primary outcome analysis: 236 were randomized to the liberal transfusion strategy group and 239 to the restrictive transfusion strategy group. Both groups had similar baseline characteristics. In total, 534 RBCTs were administered in the liberal transfusion strategy group, compared with 246 RBCTs in the restrictive group. At 180 days after randomization, 138 patients (58.5%) in the liberal group had unfavorable neurological outcome compared with 161 patients (67.4%) in the restrictive group (relative risk [RR], 0.86 [95% CI, 0.75-1.00]; P = .047; fragility index = 1). There were no significant differences in the occurrence of secondary outcomes (eg, 28-day mortality: 42 of 240 [17.5%] vs 51 of 244 [20.9%]; RR, 0.84 [95% CI, 0.58-1.21]; P = .34) or serious adverse events (eg, RR, 1.13 [95% CI, 0.88-1.43]; P = .34 for infection and RR, 0.87 [95% CI, 0.40-1.90]; P = .72 for cerebral ischemia). After adjustment for several confounders, being randomized to the liberal group was associated with a lower observed probability of unfavorable neurological outcome (odds ratio, 0.60 [95% CI, 0.38-0.94]; P = .03). Conclusions and Relevance: In this secondary analysis of a multicenter randomized clinical trial, a liberal RBCT strategy was associated with a lower risk than a restrictive RBCT strategy of unfavorable neurological outcome at 180 days among patients with TBI. These findings should be interpreted with caution in light of the inherent uncertainty of the estimate. Trial Registration: ClinicalTrials.gov Identifier: NCT02968654.