Lack of association between chronological age and fisher group and poor outcomes in older patients with severe-grade aneurysmal subarachnoid hemorrhage: a nationwide registry study in Japan.

Older age and Fisher group scores predict poor outcomes in patients with aneurysmal subarachnoid hemorrhage (aSAH). However, among aging societies, treatment indications and decisions in older patients with severe-grade aSAH (World Federation of Neurosurgical Societies [WFNS] grade IV or V) remain poorly understood. Therefore, we aimed to identify the risk factors associated with poor outcomes in non-older and older patients with severe-grade aSAH. We analyzed a database of patients with aSAH treated between April 2007 and December 2019 in Japan and divided them into either the non-older (< 75 years) or older group (age ≥ 75 years) to identify factors associated with poor outcomes (modified Rankin Scale score [mRS] 3-6) at discharge. The data analyzed included patient demographics, comorbidities, aneurysm characteristics, Fisher group, WFNS grade, treatment method, and mRS score at discharge. Among the 5,095 patients, 1,303 (986 non-older and 317 older) were classified as having severe-grade aSAH. In non-older patients, chronological age (odds ratio [OR], 1.04; 95% confidence interval [CI], 1.03-1.05) and Fisher groups 3 and 4 were associated with poor outcomes as compared with Fisher group 1 + 2 (OR, 2.98; 95% CI, 1.59-5.58 and OR, 5.49; 95% CI, 2.86-10.54, respectively). However, chronological age and Fisher groups 3 and 4 were not associated with poor outcomes in older patients with severe-grade aSAH. This study suggests that outcomes in older patients with severe-grade aSAH cannot be predicted in the same manner as in non-older patients. Further research on potential prognostic factors, such as biological age, is warranted. Clinical trial number Not applicable.