Isolated Severe Traumatic Brain Injuries: Association of Blood Alcohol Levels With the Severity of Injuries and Outcomes

Background: Traumatic brain injury is a common cause of death after traumatic insults. Alcohol intoxication is a recognized contributor to the occurrence of these injuries. The specific effects of alcohol exposure on injury severity and subsequent outcomes, however, remain controversial. The aim of this study was to investigate the relationship between blood alcohol levels (BAL) and outcomes in patients with isolated severe traumatic brain injuries (sTBI). Methods: During the calendar year 2003, as part of a pilot project, the Los Angeles County Department of Health Services obtained routine BAL on all patients transported to any of its 13 trauma centers. This study analyzes the effect of BAL on outcomes in patients with isolated sTBI (head Abbreviated Injury Scale (AIS) score ≥3; extracranial AIS score <3). The Low/No ethanol (ETOH) group included patients with negative or low (<0.08 mg/dL) BAL. Patients with BAL ≥0.08 mg/dL constituted the high ETOH group. Logistic regression was performed to determine whether alcohol levels had an independent association with outcomes. Results: There were 815 patients with isolated severe head injuries. Overall, 468 patients (57%) constituted the Low/No ETOH group, and 347 (43%) the high ETOH group. Alcohol levels were not significantly associated with severity of injury, hypotension at admission, Glasgow Coma Scale score, incidence of major complications, and intensive care unit or hospital length of stay. However, adjusted mortality was significantly lower in the high ETOH group when compared with the Low/No ETOH (8.9% vs. 17.1%; adjusted odds ratio: 0.60, 95% confidence interval: 0.37-0.96, p = 0.037). In the subgroup of patients with Injury Severity Score >15 the relative risk for mortality in the high ETOH group was significantly lower than in patients with Low/No ETOH. There was also an increased survival with high ETOH in patients with Injury Severity Score >25, but this was not statistically significant. Conclusions: Among patients with isolated sTBI, BAL do not seem to be associated with overall injury severity, head injury severity, or the occurrence of major morbidities. Similarly, hospital and intensive care unit lengths are not affected by high admission BAL level. The adjusted overall in-hospital mortality, however, is significantly lower in patients presenting with the high BAL (≥0.08 g/dL) after isolated sTBI.