CURRENT IMPLICATIONS FOR THE EFFICACY OF NONINVASIVE SCREENING FOR OCCULT INTRACRANIAL ANEURYSMS IN PATIENTS WITH A FAMILY HISTORY OF ANEURYSMS

Although the technology exists for accurate noninvasive screening for intracranial aneurysms, the efficacy of screening depends on several k ey parameters of the natural history of aneurysms. Recent studies sugg est that the prevalence of intracranial aneurysms may reach 20% in the subpopulation of patients with a family history of these lesions; oth er key parameters are less certain. The authors investigated factors t hat impact the efficacy of screening to establish interim guidelines. Three plausible models for the natural history of aneurysms were const ructed. For each model the monetary cost of screening and the average gain in life expectancy were computed for a range of screening ages an d prevalence rates. It is shown that the efficacy of screening depends on the pattern of aneurysm rupture. If aneurysms develop and rupture rapidly, then screening has no benefit. On the other hand, if aneurysm s remain at risk for some time after formation, then screening may imp rove average life expectancy depending on when it occurs. The authors recommend that patients with a positive family history of aneurysms wh o are 30 years of age or younger be screened. This recommendation is b ased on the belief that the gains attributable to screening, assuming a constant rupture rate, outweigh the losses attributable to screening using a decreasing rupture rate model.