Demographic and clinical predictors of multiple intracranial aneurysms in patients with subarachnoid hemorrhage.

OBJECTIVE Pathophysiological differences that underlie the development and subsequent growth of multiple aneurysms may exist. In this study, the authors assessed the factors associated with the occurrence of multiple aneurysms in patients presenting with aneurysmal subarachnoid hemorrhage (SAH). METHODS Consecutive patients presenting with aneurysmal SAH between 1996 and 2012 were prospectively enrolled in the Subarachnoid Hemorrhage Outcome Project. Patients harboring 1, 2, or 3 or more aneurysms were stratified into groups, and the clinical and radiological characteristics of each group were compared using multivariate logistic regression. RESULTS Of 1277 patients with ruptured intracranial aneurysms, 890 had 1 aneurysm, 267 had 2 aneurysms, and 120 had 3 or more aneurysms. On multinomial regression using the single-aneurysm cohort as base case, risk factors for patients presenting with 2 aneurysms were female sex (relative risk ratio [RRR] 1.80, p < 0.001), higher body mass index (BMI) (RRR 1.02, p = 0.003), more years of smoking (RRR = 1.01, p = 0.004), and black race (RRR 1.83, p = 0.001). The risk factors for patients presenting with 3 or more aneurysms were female sex (RRR 3.10, p < 0.001), higher BMI (RRR 1.03, p < 0.001), aneurysm in the posterior circulation (RRR 2.59, p < 0.001), and black race (RRR 2.15, p = 0.001). Female sex, longer smoking history, aneurysms in the posterior circulation, BMI, and black race were independently associated with the development of multiple aneurysms in our adjusted multivariate multinomial model. CONCLUSIONS Significant demographic and clinical differences are found between patients presenting with single and multiple aneurysms in the setting of aneurysmal SAH. These predictors of multiple aneurysms likely reflect a predisposition toward inflammation and endothelial injury.