Cost-effectiveness analysis of screening for asymptomatic, unruptured intracranial aneurysms - A mathematical model

Background and Purpose-Subarachnoid hemorrhage (SAH) due to aneurysmal rupt ure is a major cause of cerebrovascular disease-related death. This problem could be eliminated by diagnosis and successful treatment of aneurysms bef ore rupture. Recent developments in high-resolution imaging technology have made screening for unruptured aneurysms possible in the general population . Such screening has become widespread in Japan ("No Dokku," or brain check up). As a result, unruptured aneurysms are being identified with increasing frequency. However, the economic implications of treatment decisions for u nruptured aneurysms have not been analyzed. Therefore, we performed such an analysis. Methods-We used a Markov model to evaluate the cost-effectiveness of screen ing for asymptomatic, unruptured intracranial aneurysms. The model involved a set of variables describing discrete health states. Each state was assig ned a quality of life score and an associated medical cost. A comparison of the expected outcomes was then made between 2 hypothetical cohorts, one re ceiving screening and the other no screening. A sensitivity analysis was pe rformed by altering the input values within clinically reasonable ranges to reflect uncertainty in the baseline analysis and then assessing the effect s on outcomes. Results-Combining the incremental cost and effectiveness data revealed a co st per quality-adjusted life-year of $7760 for an annual rate of subarachno id hemorrhage due to unruptured aneurysms (rupture rate) of 0.02; this cost was $39 450 for a rupture rate of 0.01. There was no benefit (negative qua lity-adjusted life-year benefit) for a rupture rate of 0.005, the rupture r ate found in a recently published international cooperative study. The risk s of surgery for unruptured aneurysms and the discounting ratio used to ass ess the impact of timing of costs and benefits on future outcomes also had significant effects on the results. Other variables had little impact on co st-effectiveness. Conclusions-The cost-effectiveness of screening for an unruptured aneurysm is highly sensitive to the annual rate of subarachnoid hemorrhage due to un ruptured aneurysms. The low annual rupture rate seen in the recent large in ternational cooperative study implies that screening asymptomatic populatio ns to identify and treat unruptured aneurysms would not be cost cost-effect ive.