Retrospective evaluation of anemia and transfusion in traumatic brain injury

Despite clear evidence in critical care that blood transfusion has an adverse impact on outcome, neurosurgical textbooks still recommend transfusion of patients with traumatic brain injury (TBI) to a hematocrit (HCT) of 30%. There is little empirical evidence to support this practice. The current study addresses transfusion requirements in TBI in terms of neurologic outcome.

Retrospective record review of patients with severe TBI. Outcome measures were Glasgow Coma Scale score (GCS), Glasgow Outcome Score (GOS), and Ranchos Los Amigos Score (RLA) at hospital discharge (D/C); and GOS and Functional Independence Measures at follow-up. Association of outcomes with the number of days the HCT <30% and lowest measured HCT were evaluated.

In all, 169 patients reviewed; 150 with D/C outcome data and 72 with long-term follow-up data. Univariate analysis showed that lowest measured HCT was associated with lower D/C GCS, D/C GOS, and RLA scores. Linear regression showed that more days with HCT <30% were associated with improved neurologic outcomes measured by GOS (R2 = 0.424, p < 0.001), GCS (R2 = 0.381, p < 0.001) and RLA (R2 = 0.392, p < 0.001) scores on D/C. Both transfusion and lowest measured HCT were significantly associated with all lower outcome scores on D/C. Additional factors with adverse impact on outcome were head Abbreviated Injury Score (AIS), Injury Severity Score, hyperglycemia, and hypotension. Long-term outcomes were only significantly associated with head AIS.

Patients with severe TBI should not have a different transfusion threshold than other critical care patients. Prospective studies are needed to evaluate the effects of anemia in TBI.