Role of Apolipoprotein E Genotypes in Aneurysmal Subarachnoid Hemorrhage: Susceptibility, Complications, and Prognosis.

BACKGROUND: Aneurysmal subarachnoid hemorrhage (aSAH) is a devastating disease. Emerging evidence has indicated that the apolipoprotein E (ApoE) genotype might be associated with the risk of aSAH as well as complications and outcomes after aSAH, although the results remain controversial.

METHODS: We searched published literature on PubMed, Embase, China National Knowledge Infrastructure, and Wanfang database to identify studies involving the ApoE genotype and aSAH. A meta-analysis was performed to summarize the relationship between ApoE genotype and aSAH, including susceptibility, complications, and prognosis.

RESULTS: Eighteen studies were considered eligible for inclusion. Generally, ε4 carriers had increased risk of aSAH (odds ratio [OR] 1.23, 95% confidence interval [CI] 1.01-1.49). White patients with the ε2/ε2 genotype had a greater risk of aSAH (OR 3.38, 95% CI 1.13-10.11). The patients with aSAH carrying the ε4 allele had an increased risk of poor outcome (OR 2.21, 95% CI 1.21-4.05) compared with non-ε4 carriers, especially in Asian patients (OR 4.99, 95% CI 1.73-14.40). ApoE ε4 carriers have increased risk of delayed ischemic neurologic deficit compared with non-ε4 carriers in the overall population. No significant difference was detected regarding the effect of certain ApoE genotypes on aSAH admission severity, rebleeding, or cerebral vasospasm after aSAH.

CONCLUSIONS: We found that the ApoE genotype was significantly associated with aSAH risk, whereas its effect on certain ethnic populations differs. Patient carrying the ε4 allele might have a worse outcome, whereas current evidence was insufficient to prove the association between ApoE genotypes and post-SAH complications.