Long-term risk of aneurysmal subarachnoid hemorrhage after a negative aneurysm screen

Abstract

Objective: The objective was to assess the risk of aneurysmal subarachnoid hemorrhage (aSAH) in the initial 15 years after negative aneurysm screening in persons with one first-degree relative with aSAH.

Methods: From a cohort of first-degree relatives of patients with aSAH who underwent screening between 1995 and 1997 (n = 626), we included those with a negative screening (n = 601). We retrieved all causes of death and sent a questionnaire to screenees who were still alive. If aSAH was reported, we reviewed all medical data. We assessed the incidence of aSAH in this cohort with survival analysis and calculated an incidence ratio by dividing the observed incidence with the age- and sex-adjusted incidence in the general population.

Results: Of the 601 screenees, 3 had aSAH during 8,938 follow-up patient-years (mean 14.9 years). After 15 years, the cumulative incidence was 0.50% (95% confidence interval: 0.00%-1.06%) with an incidence rate of 33.6 per 100,000 person-years; the incidence rate ratio was 1.7 (95% confidence interval: 0.3-5.7).

Conclusions: In the first 15 years after a negative screening, the risk of aSAH in persons with one first-degree relative with aSAH is not nil, but in the range of that in the general population, or even higher. Whether this finding justifies serial aneurysm screening in this population requires further study.

Figure 1. Overview of the relatives eligible for the follow-up study

aSAH = aneurysmal subarachnoid hemorrhage; MRA = magnetic resonance angiography.

Figure 2. Imaging results of the 3 patients with aneurysmal subarachnoid hemorrhage during follow-up

(A) Initial negative screen magnetic resonance angiograms of patients 1, 2, and 3. (B) CT angiography showing aneurysms of the anterior communicating artery (B.1), posterior inferior cerebellar artery (B.2), and basilar artery (B.3), indicated by arrows. (C) Corresponding CT scans showing subarachnoid bleeding.