Background and Purpose A much higher
rupture rate for patients with familial
intracranial aneurysms (IA) compared with patients with sporadic IA has been reported in a study with highly selected familial
aneurysms using sporadic patients from other populations a controls. We aimed to validate these findings in a large independent series of Dutch patients with familial and sporadic IA. Methods We conducted a secondary analysis of our institutional cohort of patients who were screened for IAs between 1994 and 2016. We assessed the incidence of
aneurysmal subarachnoid hemorrhage between familial, defined as ≥2 affected first-degree relatives with
aneurysmal subarachnoid hemorrhage and unruptured IA (UIA), and sporadic patients with UIA with Cox regression analysis. Results We identified 62 familial IA patients with 91 UIA and 412 sporadic IA patients with 542 UIA. Despite familial
aneurysms being smaller and more often located at low risk sites than sporadic
IA, 3 familial patients had
aneurysmal subarachnoid hemorrhage (0.77
ruptures per 100
aneurysm-years [95% CI, 0.20-2.09]) compared with 7 sporadic patients (0.51
ruptures per 100
aneurysm-years [95% CI, 0.22-1.01]). As compared to sporadic UIA, familial UIA seems to have a 3-fold higher risk of
rupture (hazard ratio, 2.9 [95% CI, 0.6-14]). Conclusions Our results suggest a slightly increased risk of
aneurysm rupture for familial compared with sporadic IA, although we were not able to demonstrate this with statistical significance. However, the
rupture risk seems less strongly increased than found in a previous study. Based on our results, we recommend to treat familial UIA more aggressively.