Optimal PHASES Scoring for Risk Stratification of Unruptured Aneurysms

Introduction: Management of unruptured intracranial aneurysms (UIA) remains controversial, with a recent risk stratification attempt resulting in the PHASES score. The present studies aim was to assess the optimal cutoff for prediction of poor neurological outcome using the PHASES score in surgically treated aneurysms.

Methods: All patients treated with microneurosurgery at a large quaternary center for an UIA from 1/1/2014 to 12/31/2020 were retrospectively reviewed. Inclusion criteria included an admission modified Rankin Scale (mRS) of 2. PHASES score was calculated for all patients, and in patients with multiple aneurysms, the highest PHASES score was considered. Optimal cutoff for the PHASES score as well as other continuous confounding variables were determined using Euclidean distance analysis onto favorable mRS at follow-up.

Results: 425 patients were included in the analysis, of which 108 (25%) were male and the average age was 58 (sD 12). 91 (21%) had multiple aneurysms treated, and the average PHASES score was 4.61 (sD 2.72). Optimal cutoff analysis determined a PHASES score of 6 in order to maximize prediction of neurological outcome. 135 (31.8%) patients had PHASES >/= 6, and other than elements included in the PHASES score, no significant differences in comorbidities were found between the groups. Those with PHASES >/= 6 had significantly higher rates of poor neurological outcome at discharge (66 (49%) vs 95 (35%), p = 0.008) and follow-up (20 (17%) vs 18 (6.9%), p = 0.004). After adjusting for age, Charlson Commorbidities Index, nonsaccular, and aneurysm size, PHASES >/= 6 remained a significant predictor of poor neurological outcome at follow-up (OR = 2.75 [1.42 – 5.36], p = 0.003).

Conclusion : PHASES score >/= 6 demonstrated significantly greater proportions of poor outcome, suggesting that PHASES scoring at this threshold could be useful in risk stratification and management for unruptured aneurysms.