Outcome predictors in older adults (≥ 65 years) with aneurysmal subarachnoid haemorrhage

While advanced age is an established risk factor for poor outcomes in aneurysmal subarachnoid haemorrhage (aSAH), prognostic tools specific to older adults, remain limited. This study aims to characterise the utility of frailty indices, in addition to established outcome predictors, in older adults with aSAH. Cohort study of patients aged ≥ 65 years with aSAH referred from 2016 to 2022. Demographics, clinical, radiological and outcome data were recorded prospectively. Frailty indices were retrospectively assigned: the 5-item modified frailty index (mFI)-5, 11-item mFI (mFI-11), and electronic frailty index (EFI). 378 referred patients aged ≥ 65 years. 264/378 (69.84%) were transferred to a neurosurgical unit. 248/378 (65.61%) underwent aneurysm treatment (surgical 30/248, 12.09%; endovascular 218/248, 87.9%). 187/378 (49.47%) of referred and 66/248 (26.62%) of treated cases were poor World Federation of Neurosurgical Societies (WFNS) grade. Poor outcomes (death/dependence) occurred in 80/248 (32.26%) of treated cases. WFNS grades IV (adjusted odds ratio aOR: 5.08, 95% CI: 1.84–15.08) and V (aOR: 19.76, 95% CI: 5.78–74.18) were the strongest independent predictors of three-month mortality, followed by rebleeding (aOR: 5.93, 95% CI: 2.12–16.71), age (aOR: 1.10, 95% CI: 1.03–1.18), cerebrospinal fluid (CSF) diversion requirement (aOR: 3.11, 95% CI: 1.27–7.84) and the EFI (aOR: 1.23, 95% CI: 1.00-1.49). All WFNS grades independently predicted three-month functional status, particularly grades IV (aOR: 0.11, 95% CI: 0.05–0.25) and V (aOR: 0.03, 95% CI: 0.01–0.11). Additional independent predictors of three-month independence included the EFI (aOR: 0.77, 95% CI: 0.64–0.91), CSF diversion requirement (aOR: 0.39, 95% CI: 0.19–0.81), angiographic vasospasm (aOR: 0.44, 95% CI: 0.23–0.85), and age (aOR: 0.93, 95% CI: 0.88–0.99). WFNS grade was the most significant predictor of poor outcomes. The EFI emerged as a significant outcome predictor, however further study is required to fully determine the impact of frailty indices on outcomes in aSAH.