Application of unruptured aneurysm scoring systems to a cohort of ruptured aneurysms: are we underestimating rupture risk?

The predictive values of current risk stratification scales such as the Unruptured Intracranial Aneurysm Treatment Score (UIATS) and the PHASES score are debatable. We evaluated these scores using a cohort of ruptured intracranial aneurysms to simulate their management recommendations had the exact same patients presented prior to rupture. A prospectively maintained database of ruptured saccular aneurysm patients presenting to our institution was used. The PHASES score was calculated for 992 consecutive patients presenting between January 2002 and December 2018, and the UIATS was calculated for 266 consecutive patients presenting between January 2013 and December 2018. A shorter period was selected for the UIATS cohort given the larger number of variables required for calculation. Clinical outcomes were compared between UIATS-recommended "observation" aneurysms and all other aneurysms. Out of 992 ruptured aneurysms, 54% had a low PHASES score (≤5). Out of the 266 ruptured aneurysms, UIATS recommendations were as follows: 68 (26%) "observation," 97 (36%) "treatment," and 101 (38%) "non-definitive." The UIATS conservative group of patients developed more SAH-related complications (78% vs. 65%, p=0.043), had a higher rate of non-home discharge (74% vs. 46%, p<0.001), and had a greater incidence of poor functional status (modified Rankin scale >2) after 12-18 months (68% vs. 51%, p=0.014). Current predictive scoring systems for unruptured aneurysms may underestimate future rupture risk and lead to more conservative management strategies in some patients. Patients that would have been recommended for conservative therapy were more likely to have a worse outcome after rupture.