Association of Apolipoprotein E Polymorphism With Outcome After Aneurysmal Subarachnoid Hemorrhage

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Abstract
Background and Purpose —Variation in the outcome after aneurysmal subarachnoid hemorrhage (SAH) is not fully explained by known prognostic factors. APOE genotype is the most important genetic determinant of susceptibility to Alzheimer’s disease, and it is also shown to be associated with the outcome after traumatic brain injury. We studied the association of apolipoprotein E polymorphism with the outcome after aneurysmal SAH. Methods —A total of 160 consecutive patients were admitted after SAH to a neurosurgical unit. The clinical assessment after the SAH was performed with the Hunt and Hess grading scale. The severity of the bleeding as visualized on CT was assessed by Fisher’s grading system. Outcome was assessed with the Glasgow Outcome Scale. APOE genotypes were determined by polymerase chain reaction–restriction fragment length polymorphism. Results —126 patients had aneurysmatic SAH, and detailed information on outcome and APOE genotype was available for 108 patients (86%). Sixteen (40%) of 40 patients with APOE ε4 had an unfavorable outcome compared with 13 (19%) of 68 without the APOE ε4 allele (OR 2.8, 95% CI 1.18 to 6.77). Association was more significant after adjustment for age, rebleeding, clinical status on admission, and CT scan findings (OR 7.1, 95% CI 1.9 to 26.3; P =0.0035). Conclusions —Our findings show a significant genetic association of APOE polymorphism with outcome after spontaneous aneurysmal SAH. Genetic factors thus seem to explain a part of individual differences in the recovery of SAH.