Risk factors of short-term poor functional outcomes and long-term durability of ruptured large or giant intracranial aneurysms

Objective: Aneurysmal subarachnoid hemorrhage (SAH) is associated with high morbidity and mortality rates. In particular, functional outcomes of SAH caused by large or giant (≥ 10 mm) ruptured intracranial aneurysms are worsened by high procedure-related complication rates. However, studies describing the risk factors for poor functional outcomes specific to ruptured large/giant aneurysms are sparse. In addition, high recurrence and rebleeding rates following treatment of such aneurysms remain a concern. This study aimed to clarify the specific risk factors for poor short-term outcomes and long-term durability of SAH due to ruptured large/giant intracranial aneurysms using a multicenter observational database in Japan.

Methods: Data were obtained from 8 institutions participating in a multicenter repository of aneurysmal SAH in Japan. Among 5095 consecutive registered patients with SAH patients, 416 patients with SAH caused by ruptured large/giant (≥ 10 mm) saccular intracranial aneurysms were included. The authors investigated the risk factors for poor functional outcomes in patients with such aneurysms using multivariable analyses and subsequently investigated the interaction between these risk factors. The association between the treatment modality (direct surgery or endovascular therapy) and functional outcomes were finally analyzed using a propensity score-based method. The long-term durability of the treated aneurysms was evaluated by analyzing rebleeding.

Results: Poor functional outcomes (modified Rankin Scale score ≥ 3) at discharge were observed in 251 (60.3%) patients. Increasing aneurysm size was significantly associated with poor functional outcomes (OR 1.13, 95% CI 1.04-1.22; p = 0.003) by a multivariable logistic regression analysis, and such negative effects were more prominent in younger patients, those with a good initial neurological grade, and those treated with direct surgery by interaction analyses. Propensity score-based analysis revealed that patients treated with endovascular therapy had a higher chance of better functional outcomes (OR 1.56, 95% CI 1.41-1.71; p = 0.03). Rebleeding 1 year after treatment was more frequent in the endovascular therapy (4.8%) than in the direct surgery (0.0%) group by survival analysis (p = 0.008, log-rank test).

Conclusions: Increasing aneurysm size was identified as a risk factor for poor functional outcomes after SAH due to large/giant aneurysms and was affected by the interaction with other conventional risk factors. Endovascular therapy was more likely to be associated with better short-term outcomes; however, a higher delayed rebleeding rate after 1 year was a concern.