Experimental studies have shown numerous neuroprotective properties of alcohol (“ethanol”) after traumatic brain injury, but clinical studies have provided conflicting results.
The authors of a recent study assessed the relationship between positive blood alcohol concentration (BAC) on hospital admission and mortality after moderate to severe traumatic brain injury (TBI). The authors searched 8 databases for observational studies reported between January 1, 1990, and October 7, 2013, and investigated the effect of BAC on mortality after moderate to severe TBI. Reviews of each study were conducted, and data were extracted according to the MOOSE and PRISMA guidelines.
Eleven studies with a total of 95,941 patients (42% BAC positive and 58% BAC negative) were identified for the primary analysis (overall mortality 12%). Primary analysis showed a significantly lower risk of death for BAC-positive patients compared with BACnegative patients (crude mortality 11.0% vs 12.3%, pooled OR 0.84 [95% CI 0.81-0.88]), although flawed by heterogeneity (I2 = 68%). Multiple sensitivity analyses, including 55,949 and 51,772 patients, yielded similar results to the primary analysis (crude mortality 12.2% vs 14.0%, pooled OR 0.87 [95% CI 0.83-0.92] and crude mortality 8.7% vs 10.7%, pooled OR 0.78 [95% CI 0.74-0.83]) but with good study homogeneity (I2 = 36% and 14%).
Positive BAC was significantly associated with lower mortality rates in moderate to severe TBI, the authors conclude. Whether this observation is due to selection bias or neuroprotective effects of alcohol remains unknown. Future prospective studies adjusting for TBI heterogeneity are advocated to establish the potential favourable effects of alcohol on outcome after TBI.
Source: Alcohol and mortality after moderate to severe traumatic brain injury: a meta-analysis of observational studies. Raj R, Mikkonen ED, Siironen J, Hernesniemi J, Lappalainen J, Skrifvars MB. J Neurosurg. 2015 Oct 23:1-9.