The impact of anemia in moderate to severe traumatic brain injury

Purpose: The impact of anemia and restrictive transfusion strategies in traumatic brain injury (TBI) is unclear. The purpose of this study was to examine the outcome of varying degrees of anemia in patients who have sustained a TBI.

Methods: We performed a retrospective study of all adult patients with isolated blunt TBI admitted between January 2003 and June 2010. The impact of increasing severity of anemia (Hb ≤8, ≤9, or ≤10 g/dl measured on three consecutive draws within the first 7 days of admission) and transfusions on complications, length of stay, and mortality was examined using univariate and multivariate analysis.

Results: Of the 31,648 patients with blunt trauma admitted to the trauma service during the study period, 812 had an isolated TBI, among which 196 (24.1 %) met at least one of the anemia thresholds within the first 7 days [78 % male, mean age 47 ± 23 years, Injury Severity Score 16 ± 8, and head Abbreviated Injury Scale 3.3 ± 1.0]. Using a logistic regression model, anemia even as low as 8 g/dl was not associated with an increase in mortality [AOR8 = 0.8 (0.2, 3.2), p = 0.771; AOR9 = 0.8 (0.4, 1.6), p = 0.531; AOR10 = 0.6 (0.3, 1.3), p = 0.233] or complications. However, for all patients, the transfusion of packed red blood cells was associated with a significant increase in septic complications [AOR = 3.2 (1.5, 13.7), p = 0.030].

Conclusion: The presence of anemia in patients with TBI as low as 8 g/dl was not associated with increased mortality or complications, while the transfusion of red blood cells was associated with a significant increase in septic complications. Prospective evaluation of an optimal transfusion trigger in head-injured patients is warranted.