Prediction of outcomes for ruptured aneurysm surgery: The southwestern aneurysm severity index

Background and Purpose - Predicting long-term functional outcomes after intracranial aneurysmal rupture can be challenging. We developed and validated a scoring system - the Southwestern Aneurysm Severity Index - that would predict functional outcomes at 1 year after clipping of ruptured aneurysms. Methods - Ruptured aneurysms treated microsurgically between 2000 and 2014 were included. Outcome was defined as Glasgow Outcome Score (ranging from 1, death, to 5, good recovery) at 1 year. The Southwestern Aneurysm Severity Index is composed of multiple prospectively recorded patient demographic, clinical, radiographic, and aneurysm-specific variables. Multivariable analyses were used to construct the best predictive models for patient outcomes in a random 50% of the cohort and validated in the remaining 50%. A scoring system was created using the best model. Results - We identified 527 eligible patients. The Glasgow Outcome Score at 1 year was 4 to 5 in 375 patients (71.2%). In the multivariable logistic regression, the best predictive model for unfavorable outcome included intracerebral hemorrhage (odds ratio [OR], 2.53; 95% CI, 1.55-4.13), aneurysmal size ≥20 mm (OR, 6.07; 95% CI, 1.92-19.2), intraventricular hemorrhage (OR, 2.56; 95% CI, 1.15-5.67), age >64 (OR, 3.53; 95% CI, 1.70-7.35), location (OR, 1.82; 95% CI, 1.10-3.03), and hydrocephalus (OR, 2.39; 95% CI, 1.07-5.35). The Southwestern Aneurysm Severity Index predicts Glasgow Outcome Score at 1 year with good discrimination (area under the receiver operating characteristic curve, derivation: 0.816, 95% CI, 0.759-0.873; validation: 0.803, 95% CI, 0.746-0.861) and accurate calibration (R²=0.939). Conclusions - The Southwestern Aneurysm Severity Index has been internally validated to predict 1 year Glasgow Outcome Scores at initial presentation, thus optimizing patient or family counseling and possibly guiding therapeutic efforts.