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

Abstract

Background and Purpose Prediction of intracranial aneurysm growth risk can assist physicians in planning of follow-up imaging of conservatively managed unruptured intracranial aneurysms. We therefore aimed to externally validate the ELAPSS (Earlier subarachnoid hemorrhage, aneurysm Location, Age, Population, aneurysm Size and Shape) score for prediction of the risk of unruptured intracranial aneurysm growth. Methods From 11 international cohorts of patients ≥18 years with ≥1 unruptured intracranial aneurysm and ≥6 months of radiological follow-up, we collected data on the predictors of the ELAPSS score, and calculated 3- and 5-year absolute growth risks according to the score. Model performance was assessed in terms of calibration (predicted versus observed risk) and discrimination (c-statistic). Results We included 1,072 patients with a total of 1,452 aneurysms. During 4,268 aneurysm-years of follow-up, 199 (14%) aneurysms enlarged. Calibration was comparable to that of the development cohort with the overall observed risks within the range of the expected risks. The c-statistic was 0.69 (95% confidence interval [CI], 0.64 to 0.73) at 3 years, compared to 0.72 (95% CI, 0.68 to 0.76) in the development cohort. At 5 years, the c-statistic was 0.68 (95% CI, 0.64 to 0.72), compared to 0.72 (95% CI, 0.68 to 0.75) in the development cohort. Conclusions The ELAPSS score showed accurate calibration for 3- and 5-year risks of aneurysm growth and modest discrimination in our external validation cohort. This indicates that the score is externally valid and could assist patients and physicians in predicting growth of unruptured intracranial aneurysms and plan follow-up imaging accordingly.

Risk factors for the progression of unruptured intracranial aneurysms in patients followed by CT/MR angiography

“…Although two studies showed that ELAPSS score was associated with IA growth (18,20), the c-statistic was 0.72 in the development cohort at 3 and 5 years (20). Meanwhile, in a retrospective study of ruptured IAs, 45.5% of patients were classified as low or intermediate risk using the ELAPSS score (31).…”

“…Thus, determining the risk factors for UIA progression would be of substantial clinical value. Many previous studies have investigated the risk factors for IA progression (2,4,6,(8)(9)(10)(11)(12)(13)(14)(15)(16)(17)(18)(19)(20). However, the results are not consistent.…”

“…However, the PHASES score is a model that provides the absolute risk of rupture for IAs, which is not very suitable for the prediction of IA growth (17). Recently, two studies confirmed the validation of the ELAPSS score for the prediction of UIA progression (18,20). However, it is not clear whether this score has predictive value for UIAs in the Chinese population.…”

Diagnosis and Treatment of Unruptured Intracranial Aneurysms and Aneurysmal Subarachnoid Hemorrhage

“…Recent literature has suggested that several groups of aneurysms have a higher risk of growth than others, and these patients may benefit from shorter intervals of repeated surveillance imaging. 129,130 The ELAPSS score has been used to predict the risk of aneurysmal growth, such that earlier SAH, location of aneurysm, age >60 years, population, and size and shape of the UIA were found to be predictors of aneurysmal growth. 129 This score was externally validated and was found to show accurate calibration for 3-and 5-year risks of aneurysm growth.…”

“…As a result, this score may assist patients and clinicians in predicting the growth of a UIA and in planning for followup imaging accordingly. 130 Furthermore, in elderly patients (>75 years) and those with significant comorbidities or a limited life expectancy, conservative management and no follow-up may be needed, even with large aneurysms, because it is highly unlikely that these patients will undergo preventive aneurysm treatment.…”