Association Between Severe Anaemia and Outcome in Moderate and Severe Traumatic Brain Injury: A Retrospective Cohort Study

Abstract

Background: Anaemia is common among patients with traumatic brain injury (TBI), and it might contribute to the development of secondary brain injury. However, the impact of anaemia on outcome among TBI patients remains controversial. The aim of this study was to investigate the association between acute anaemia and short-term neurological outcome and mortality among patients with moderate to severe TBI. Methods: The retrospective cohort study included all successive patients admitted to Tampere University Hospital's emergency department with moderate to severe TBI between August 2010 and July 2012. Information on patient demographics, trauma-related characteristics and post-traumatic care was collected, including all in-hospital haemoglobin (Hb) values. Hb concentration below 100 g/L at any point during the hospitalisation was defined as severe anaemia. The main outcome variable was the Glasgow Outcome Scale (GOS) at hospital discharge, dichotomized as poor (GOS 1 to 3) and good (GOS 4 to 5) outcome. The secondary outcome variables were mortality rates at 3, 6 and 12 months after TBI. Results: A total of 145 patients with moderate to severe TBI met the inclusion criteria. Severe anaemia was detected in 45.5%. In univariate analyses, severe anaemia was associated with poor unfavourable functional outcome at hospital discharge (83.3% vs. 55.6%, p < 0.001), and higher 3-month, 6-month and 12-month mortality rates (28.8% vs. 13.9%, p = 0.028; 30.3% vs. 16.5%, p = 0.048; 36.4% vs. 17.7%, p = 0.011, respectively). In multivariable analysis, severe anaemia was independently associated with unfavourable functional outcome (OR 4.06, 95% CI 1.54–10.72, p = 0.005), but not with higher long-term mortality. Conclusion: Among patients with moderate to severe TBI, severe anaemia with an Hb level below 100 g/L during hospitalisation was independently associated with unfavourable functional outcome at hospital discharge. Editorial Comment: For cases with severe traumatic brain injury, managing oxygen carrying capacity is one important factor. In this single center cohort, severe anemia documented at any point in the hospitalization was associated with worse neurological outcome.