Optimal PHASES scoring for risk stratification of surgically treated unruptured aneurysms

The PHASES (Population, Hypertension, Age, Size, Earlier subarachnoid hemorrhage, Site) score was developed to facilitate risk stratification for management of unruptured intracranial aneurysms (UIAs). This study aimed to identify the optimal PHASES score cutoff for predicting neurological outcomes in patients with surgically treated aneurysms. All patients who underwent microneurosurgical treatment for UIA at a large quaternary center from January 1, 2014, to December 31, 2020, were retrospectively reviewed. Inclusion criteria included a modified Rankin Scale (mRS) score of ≤2 at admission. The primary outcome was 1-year mRS score, with a “poor” neurological outcome defined as an mRS score >2. In total, 375 patients were included in the analysis; The mean (SD) PHASES score for the entire study population was 4.47 (2.67). Of 375 patients, 116 (31%) had a PHASES score ≥6, which was found to maximize prediction of poor neurological outcome. Patients with PHASES scores ≥6 had significantly higher rates of poor neurological outcome than patients with PHASES scores <6 at discharge (58 [50%] vs 90 [35%], p=0.005) and follow-up (20 [17%] vs 18 [6.9%], p=0.002). After adjusting for age, Charlson Comorbidity Index score, nonsaccular aneurysm, and aneurysm size, PHASES score ≥6 remained a significant predictor of poor neurological outcome at follow-up (odds ratio, 2.75; 95% confidence interval, 1.42-5.36, p=0.003). In this retrospective analysis, a PHASES score ≥6 was associated with significantly greater proportions of poor outcome, suggesting that awareness of this threshold in PHASES scoring could be useful in risk stratification and UIA management.