Retrospective External Validation of the ELAPSS Score for the Prediction of Unruptured Intracranial Aneurysm Growth Risk

INTRODUCTION: This study aimed to evaluate the accuracy of the Earlier Subarachnoid Hemorrhage, Aneurysm Location, Age, Population, Aneurysm Size, And Shape (ELAPSS) score in predicting the growth risk of unruptured intracranial aneurysms across different patient subgroups. METHODS: Between 2002 and 2021, we retrospectively included patients with saccular intracranial aneurysms who underwent at least two serial angiographic imaging studies at a single tertiary center. Imaging modalities included computed tomography angiography, magnetic resonance angiography, and digital subtraction angiography, with a minimum follow-up of six months. ELAPSS score components were recorded at diagnosis, and absolute growth risks at 3, 5, 10, 15, and 16 years were calculated. RESULTS: A total of 483 patients with 563 aneurysms were analyzed, accounting for 2,766 aneurysm- years of follow-up. Aneurysm growth was observed in 86 aneurysms (15.2%). Over a 16- year follow-up period, cumulative growth risk was significantly lower in the low-risk group compared with the intermediate- and high-risk groups. DISCUSSION: Although the ELAPSS score demonstrated long-term risk stratification for aneurysm growth, heterogeneity in patient and aneurysm characteristics may limit its accuracy for individualized clinical decision-making. CONCLUSION: This external validation study suggests that caution is warranted when applying the ELAPSS score to guide treatment decisions for unruptured intracranial aneurysms.