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, derivation0.816, 95% CI, 0.759−0.873; validation0.803, 95% CI, 0.746−0.861) and accurate calibration (R=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.