For ruptured cerebral aneurysms over 90 years of age, the outcome and the safety after endovascular treatment are not well-known. This multicenter retrospective registry enrolled patients with ruptured cerebral aneurysms after endovascular treatment from January 2015 to December 2019 in Japan. We investigated differences between the patients over 90 years (age ≥ 90) and those under 90 years of age (age <
90). The primary outcome was defined as a modified Rankin scale 0-2 at 30 days. Secondary outcomes were all-cause death and returned to premorbid modified Rankin scale at 30 days. Safety outcomes were the incidence of ischemic stroke and technical complications. Among 8,024 patients with aneurysm, 204 were aged ≥ 90 years and 7,820 were <
90 years, those of median age were 92 and 65 years. The proportion of females and premorbid modified Rankin scale was higher in the age ≥ 90 group (n [%]
191 [93.6] vs. 5,395 [69.0], median [interquartile range]
1 [0-2] vs. 0 [0-0]). The modified Rankin scale 0-2 at 30 days was lower in age ≥ 90 patients than in age <
90 patients (13.2% vs. 56.2%, adjusted odds ratio [95% confidence intervals]
0.13 [0.08-0.21]). In age ≥ 90 patients, all-cause death was significantly higher (adjusted odds ratio [95% confidence intervals]
1.85 [1.19-2.86]) and returned to premorbid modified Rankin scale was significantly lower (adjusted odds ratio [95% confidence intervals]
0.26 [0.17-0.39]). However, safety outcomes were not significantly different between both groups. In this population undergoing endovascular treatment for ruptured cerebral aneurysms, patients older than 90 years had a poor prognosis but no difference in having perioperative complications.