Restrictive vs. Liberal Transfusion Strategy in Critically Ill Patients with Acute Brain Injury: A Systematic Review and Meta-analysis.

The indications of red blood cell transfusions in the absence of life-threatening bleeding in neurocritical individuals are controversial. Recently, three large randomized controlled trials assessed transfusion strategies in this population, allowing an update of a previous meta-analysis, including a sample seven times bigger than the one analyzed previously. We performed a systematic review and updated meta-analysis of liberal versus restrictive transfusion strategy in patients with acute brain injury, comprising traumatic brain injury (TBI), intracerebral hemorrhage, and subarachnoid hemorrhage. A review protocol was registered on PROSPERO (CRD42024616143). We systematically searched PubMed, Embase, and the Cochrane Central Register of Controlled Trials for randomized controlled trials comparing liberal versus restrictive transfusion strategy in neurocritical patients. We used Review Manager 5.4 to apply a random-effects model to pool risk ratios (RRs) and 95% confidence intervals (CIs), as available in the individual studies. Quality assessment was performed through the Cochrane Risk of Bias assessment tool (RoB 2.0 tool). Six randomized clinical trials were included, comprising 2,497 patients, of whom 1,431 presented with TBI. The liberal transfusion strategy led to statistically significant lower rates of unfavorable neurological outcomes compared to the restrictive strategy (RR 0.89; 95% CI 0.83-0.96; p = 0.002; I = 0%). Although a trend favoring the liberal strategy was observed in most mortality and length of stay outcomes, the pooled analysis did not identify statistically significant differences between the two groups. TBI subgroup analysis led to similar results when compared to the general pooled analysis. The main study limitations include the limited number of studies, the imbalance in study weights within the analyses, and the presence of significant heterogeneity. In conclusion, our results suggest that a liberal transfusion strategy may be beneficial to neurocritical patients in terms of neurological outcome when compared to the restrictive strategy, although our results should be interpreted with caution. Further investigation is needed to provide support for updating guidelines for neurocritical care.