Risk Prediction of New Intracranial Aneurysms at Follow-Up Screening in People With a Positive Family History

BACKGROUND: In first-degree relatives of patients with aneurysmal subarachnoid hemorrhage (aSAH), the risk of an intracranial aneurysm can be predicted at initial screening but not at follow-up screening. We aimed to develop a model for predicting the probability of a new intracranial aneurysm after initial screening in people with a positive family history of aSAH. METHODS: In a prospective study, we obtained data from follow-up screening for aneurysms of 499 subjects with ≥2 affected first-degree relatives. Screening took place at the University Medical Center Utrecht, the Netherlands, and the University Hospital of Nantes, France. We studied associations between potential predictors and the presence of aneurysms using Cox regression analysis and the predictive performance at 5, 10, and 15 years after initial screening using C statistics and calibration plots, while correcting for overfitting. RESULTS: In 5050 person-years of follow-up, intracranial aneurysms were found in 52 subjects. The risk of aneurysm at 5 years was 2% to 12%, at 10 years, 4% to 28%, and at 15 years, 7% to 40%. Predictors were female sex, history of intracranial aneurysms/aneurysmal subarachnoid hemorrhage, and older age. The sex, previous history of intracranial aneurysm/aSAH, older age score had a C statistic of 0.70 (95% CI, 0.61-0.78) at 5 years, 0.71 (95% CI, 0.64-0.78) at 10 years, and 0.70 (95% CI, 0.63-0.76) at 15 years and showed good calibration. CONCLUSIONS: The sex, previous history of intracranial aneurysm/aSAH, older age score provides risk estimates for finding new intracranial aneurysms at 5, 10, and 15 years after initial screening, based on 3 easily retrievable predictors; this can help to define a personalized screening strategy after initial screening in people with a positive family history for aSAH.