Haemoglobin Threshold for Red Blood Cell Transfusion in Traumatic Brain Injury: a Systematic Review and Meta-Analysis

Background Traumatic brain injury (TBI) is a significant and growing worldwide healthcare burden. Minimising brain hypoxia is important in preventing secondary brain injury. Anaemia is common in TBI patients, but there is little evidence as to which haemoglobin (Hb) threshold transfusion should be considered in TBI patients. Methods We searched Cochrane Central Register of Controlled Trials, MEDLINE, Embase, CINAHL, and Web of Science up to June 2020. We also searched clinical trial registers, conference proceedings, and reference lists from previous systematic reviews and included studies. We included randomised studies comparing high verses low Hb threshold for red blood cell transfusion in TBI patients. The primary outcome of interest was all-cause mortality, and secondary outcomes were transfusion related adverse events and favourable outcome (Glasgow Outcome Scale, GOS). Results We included 3 RCTs involving 311 participants. Our analysis showed no difference in all-cause mortality (3–6 months) (OR 1.17 (95% CI 0.64 to 2.13)) and no difference in GOS (OR 1.10 (95% CI 0.65 to 1.85)) between transfusing red blood cells at 7 g/dL or at 9/10 g/dL in moderate to severe TBI. Conclusions There is no difference between a high and a low Hb threshold transfusion policy. Outcomes from high quality randomised controlled trials are awaited.