2 Stroke August 2017 Methods Inclusion / Exclusion Criteria

Between 2% and 4% of the population may potentially be diagnosed with an intracranial aneurysm (IA), and between 3 and 50 of 100 000 inhabitants per year suffer a subarachnoid hemorrhage because of aneurysm rupture (aSAH). Thus, most patients with unruptured IAs (UIAs) may remain asymptomatic. The rate of incidental diagnosis of UIA is increasing globally with the multiplication of imaging facilities. Overall, the average risk of rupture of UIA is estimated between 0.3% and >15% per 5 years (0.4–0.6 for lesions smaller than 7 mm). Preventive treatment of these aneurysms exposes patients to a risk of 1% mortality and ≈5% morbidity (<0.1% and <3%, respectively, for small lesions). The balance between risks and benefits on different management options needs to be personalized. As recently summarized, no randomized control trials have been successfully conducted to date to address the issue on the management of UIA. Only 80 patients had been recruited after nearly 3 years during the unique attempt. A decision then can only be based on (1) a consensus-based scoring strategy for the management of UIA (Unruptured Intracranial Aneurysm Treatment Score) or (2) a 5-year rupture rate estimation using the PHASES score (Table 1) model based on 8283 patients diagnosed with UIA and 29 166 patient years of follow-up. Neither decision support tool has been validated on an independent large cohort. The aim of this study is to assess whether the PHASES score is able to (1) provide decision support and matches decisions taken by expert multidisciplinary team whether to observe or intervene a diagnosed UIA, (2) classify ruptured versus unruptured aneurysm, and (3) discriminate patients at low risk of rupture from the population of patients diagnosed with UIA. Background and Purpose—The aim of this study is to assess whether the PHASES score allows to (1) match decisions taken by multidisciplinary team whether to observe or intervene, (2) classify patients being diagnosed with a ruptured versus unruptured intracranial aneurysm (UIA), and (3) discriminate patients at low risk of rupture from the population of patients diagnosed with intracranial aneurysm. Methods—Population-based prospective and consecutive data were collected between 2006 and 2014. Patients (n=841) were stratified into 4 groups: stable UIA; growing observed UIA; immediately treated UIA; and aneurysmal subarachnoid hemorrhage (aSAH). All patients initially observed were pooled in a follow-up UIA group; patients from growing observed UIA, immediately treated UIA, and aSAH were pooled in a high risk of rupture group. Results are expressed as median [quartile 1, quartile 3]. Results—PHASES scores of immediately treated UIA patients were significantly higher than follow-up UIA group (5 [3, 7] versus 2 [1, 4]). Patients diagnosed with UIA and PHASES score of >3 were more likely to be treated, and the score ≤3 was predictive for observation (areas under these curves=0.74). Odds of being diagnosed with an aSAH were associated with PHASES score of >3 (UIA, 4 [2, 6]; aSAH, 5 [4, 8]; areas under these curves=0.66). Scores of stable UIA patients were significantly lower than high risk of rupture group (2 [1, 4] versus 5 [4, 7]; stable UIA outcome prediction by PHASES score of ≤3: areas under these curves=0.76). Conclusions—There is a progression of PHASES score between stable UIA, growing observed UIA, immediately treated UIA, and aSAH groups. PHASES score of ≤3 is associated with a low but not negligible likelihood of aneurysm rupture, and specificity of the classifier is low. (Stroke. 2017;48:00-00. DOI: 10.1161/STROKEAHA.117.017391.)