Association of APOE ε4 with progressive hemorrhagic injury in patients with traumatic intracerebral hemorrhage

OBJECTIVE: The intracranial hematoma volume in patients with traumatic brain injury is a key parameter for the determination of the management approach and outcome. Apolipoprotein E (APOE) e4 is reported to be a risk factor for larger hematoma volume, which might contribute to a poor outcome. However, whether APOE e4 is related to progressive hemorrhagic injury (PHI), a common occurrence in the clinical setting, remains unclear. In this study, the authors aimed to investigate the association between the APOE genotype and occurrence of PHI. METHODS: This prospective study included a cohort of 123 patients with traumatic intracerebral hemorrhage who initially underwent conservative treatment. These patients were assigned to the PHI or non-PHI group according to the follow-up CT scan. A polymerase chain reaction and sequencing method were carried out to determine the APOE genotype. Multivariate logistic regression analysis was applied to identify predictors of PHI. RESULTS: The overall frequency of the alleles was as follows: E2/2, 0%; E2/3, 14.6%; E3/3, 57.8%; E2/4, 2.4%; E3/4, 22.8%; and E4/4, 2.4%. Thirty-four patients carried at least one allele of e4. In this study 60 patients (48.8%) experienced PHI, and the distribution of the alleles was as follows: E2/2, 0%; E2/3, 5.7%; E3/3, 22.8%; E2/4, 2.4%; E3/4, 16.3%; and E4/4, 1.6%, which was significantly different from that in the non-PHI group (p = 0.008). Additionally, the late operation rate in the PHI group was significantly higher than that in the non-PHI group (24.4% vs 11.4%, p = 0.002). Multivariate logistic regression identified APOE e4 (OR 5.14, 95% CI 2.40-11.62), an elevated international normalized ratio (OR 3.57, 95% CI 1.61-8.26), and higher glucose level (≥ 10 mmol/L) (OR 3.88, 95% CI 1.54-10.77) as independent risk factors for PHI. Moreover, APOE e4 was not a risk factor for the coagulopathy and outcome of the patients with traumatic intracerebral hemorrhage. CONCLUSIONS: The presence of APOE e4, an elevated international normalized ratio, and a higher glucose level (≥ 10 mmol/L) are predictors of PHI. Additionally, APOE e4 is not associated with traumatic coagulopathy and patient outcome.