Prediction of Outcomes for Ruptured Aneurysm Surgery

Abstract

A neurysmal subarachnoid hemorrhage (SAH) is a common neurological condition that accounts for 80% of nontraumatic SAH. 1 The incidence of aneurysmal SAH in the United States exceeds 30 000 individuals annually, and this appears to have remained steady over the past few decades. 2 It is still associated with significant morbidity and mortality, 1,3 despite recent advances in diagnostic imaging, endovascular and microsurgical techniques, as well as perioperative intensive care unit management that has increased the survival rate by ≈17%. 4-7 The clinical outcome of patients who survive an aneurysmal SAH ranges between complete independence and permanent disability. Various factors influence the prognosis of aneurysmal SAH patients. These factors can be classified into clinical factors, aneurysmal factors, and institutional factors. 8 In an era of constantly evolving precision-driven medicine, rapidly advancing endovascular technology, and high patient and family expectations, there is continuous and increasing pressure to identify patient-specific prognostic factors for a long-term outcome that would help guide immediate surgical management. Historical Perspective Since the publication of the Bramwell classification in 1933, 9 >40 aneurysm grading scales have surfaced. Most published scales, including the Hunt and Hess scales, were not statistically derived or validated but were rather the product of a consensus between experts that was based on their clinical and surgical experience. 10 These outcome scales were also treatment-independent. The surgical outcome after aneurysmal clipping in the setting of SAH is no longer solely dependent on a patient's clinical examination on presentation. We now recognize that prognosis also hinges on anatomic aneurysmal factors and patient comorbidities. The need for improved grading systems arose from the recognition that the surgical and critical care 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 (R 2 =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. (Stroke. 2019;50:595-601.