Apolipoprotein E-epsilon4 genotype predicts a poor outcome in survivors of traumatic brain injury

To determine the ability of apolipoprotein E (APOE) genotypes to predict days of unconsciousness and a suboptimal functional outcome in traumatic brain injury (TBI) survivors.

TBI is known to be associated with neuropsychological deficits and functional disability. Recent evidence indicates that APOE plays a pivotal role in CNS response to injury.

In this prospective study the authors determined the APOE genotypes and tested their ability to predict days of unconsciousness and functional outcome after at least 6 months in 69 survivors of TBI. A good functional outcome was defined as no dysarthria, behavioral abnormalities, or dysphasia; no severe cognitive abnormalities; and the ability to live independently.

The odds ratio of more than 7 days of unconsciousness was 5.69 in those with the APOE-epsilon4 allele compared with those without the epsilon4 allele (95% CI, 1.69 to 20.0; p = 0.001). Only 1 of 27 subjects (3.7%) with the epsilon4 allele had a good functional outcome compared with 13 of 42 (31.0%) of those without the epsilon4 allele (p = 0.006). The OR of a suboptimal outcome (fair or unfavorable) was 13.93 for those with the epsilon4 allele compared with those without the allele after controlling for age and time of unconsciousness (95% CI, 1.45 to 133.97; p = 0.02).

The results demonstrate a strong association between the APOE-epsilon4 allele and a poor clinical outcome, implying genetic susceptibility to the effect of brain injury. Additional studies of TBI patients are warranted to confirm their findings.