Early predictors of functional outcome in poor-grade aneurysmal subarachnoid hemorrhage: a systematic review and meta-analysis

BACKGROUND: Patients with poor-grade aneurysmal subarachnoid hemorrhage (aSAH) often receive delayed or no aneurysm treatment, although recent studies suggest that functional outcome following early aneurysm treatment has improved. We aimed to systematically review and meta-analyze early predictors of functional outcome in poor-grade aSAH patients. METHODS: We included studies investigating the association of early predictors and functional outcome in adult patients with confirmed poor-grade aSAH, defined as World Federation of Neurological Surgeons (WFNS) grade or Hunt and Hess (H–H) grade IV-V. Studies had to use multivariable regression analysis to estimate independent predictor effects of favorable functional outcome measured with the Glasgow Outcome Scale or modified Rankin Scale. We calculated pooled adjusted odds ratios (aOR) and 95% confidence intervals (CI) with random effects models. RESULTS: We included 27 studies with 3287 patients. The likelihood of favorable outcome increased with WFNS grade or H–H grade IV versus V (aOR 2.9, 95% CI 1.9–4.3), presence of clinical improvement before aneurysm treatment (aOR 3.3, 95% CI 2.0–5.3), and intact pupillary light reflex (aOR 2.9, 95% CI 1.6–5.1), and decreased with older age (aOR 0.7, 95% CI 0.5–1.0, per decade), increasing modified Fisher grade (aOR 0.4, 95% CI 0.3–0.5, per grade), and presence of intracerebral hematoma on admission imaging (aOR 0.4, 95% CI 0.2–0.8). CONCLUSIONS: We present a summary of early predictors of functional outcome in poor-grade aSAH patients that can help to discriminate between patients with favorable and with unfavorable prognosis and may aid in selecting patients for early aneurysm treatment. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12883-022-02734-x.