Individualized Upfront Treatment Selection for Aneurysmal Subarachnoid Hemorrhage and Functional Outcomes: A Single-Center Retrospective Before-and-After Cohort Study

Background/Objectives: The optimal upfront modality selection for real-world aneurysmal subarachnoid hemorrhage (aSAH) remains uncertain. We evaluated outcomes after an institutional change from an endovascular treatment (EVT)-first default to a modality-neutral individualized pathway. Methods: This single-center retrospective before-and-after cohort study included consecutive patients with aSAH who underwent aneurysm securing during two fixed time periods (pre-change: 1 May 2023 to 31 July 2024; post-change: 1 August 2024 to 31 October 2025). The primary outcome was a favorable 90-day modified Rankin Scale (mRS) score of 0–2. The primary analysis used Firth penalized logistic regression adjusted for age, pre-morbid mRS ≥ 2, and World Federation of Neurosurgical Societies grade IV–V. Conventional logistic regression and ordinal mRS shift analysis were performed as sensitivity analyses. Results: A total of 104 patients were included (pre-change, n = 48; post-change, n = 56). EVT decreased from 79.2% to 37.5%, and microsurgery increased from 20.8% to 62.5% (p < 0.001). Favorable outcomes occurred in 25/48 patients (52.1%) in the pre-change period and 36/56 patients (64.3%) in the post-change period (p = 0.235). In adjusted analyses, the post-change period was associated with favorable outcome (aOR 3.82; 95% CI, 1.31–12.79; p = 0.009), consistent with the sensitivity analysis (aOR, 4.41; 95% CI, 1.43–15.95; p = 0.009). Shift analysis also favored the post-change period (adjusted common OR, 2.36; 95% CI, 1.15–4.91; p = 0.021). Secondary outcomes and procedure-related complications were similar between the two periods. Conclusions: A shift from an EVT-first default to a modality-neutral individualized pathway was associated with more favorable adjusted 90-day functional outcomes. Multicenter confirmation is warranted.