Kara Jo Swafford, MD
Aneurysmal subarachnoid hemorrhage (SAH) accounts for 80% of nontraumatic SAH and is associated with high morbidity and mortality. Severity grading scales have been created, including the Hunt and Hess scale, which predict outcomes independent of treatment. Prognosis following microsurgical intervention not only depends on clinical presentation, but also aneurysm anatomy and comorbidities. The Southwestern Aneurysm Severity Index (SASI) was created to risk stratify patients with ruptured aneurysms for microsurgical treatment. SASI components include clinical features, imaging findings, aneurysm characteristics and re-operation.
Ban et al. designed and internally validated a scoring system to predict outcomes 1 year following microsurgical intervention for ruptured intracranial aneurysms by retrospectively analyzing prospectively collected data on SASI components for patients admitted to their institution between 2000 and 2014. Primary outcome measure was the Glasgow Outcome Scale assessed 12 months after surgery (GOS12m). Patients were divided into derivation and validation cohorts. The derivation cohort was used to develop a model with the best predictors of GOS12m. This model included age > 64, Hunt and Hess scale, the American Society of Anesthesiologists (ASA) physical status classification adjusted for neurological disease (nonneurological ASA [NNASA] scale), presence of intracerebral hemorrhage, intraventricular hemorrhage, or hydrocephalus, aneurysm location and aneurysm size ≥ 20 mm. Points were assigned to each predictor and summed to provide the Modified SASI score. The score was then validated in an independent sample from the same institution.
The Modified SASI is intended to be used on a case-by-case basis to assist with treatment decisions and predict outcomes 1 year after surgery. The data, however, were collected from a single institution and sample size was relatively small. Generalizability of the results, therefore, is uncertain and needs to be externally validated. The 5-point grading scale restricts outcomes to 1 of 5 possibilities. Another limitation is clinical outcomes were not assessed beyond 1 year. If fully validated, this score may be helpful for patient/family counseling and to guide interventions.