Abstract W MP33: Brain and Aortic Aneurysm Screening - Cost-Effectiveness of Screening for Intracranial Aneurysms

Abstract

Introduction: Intracranial aneurysm (IA) and abdominal aortic aneurysm (AAA) rupture carry high mortality (40% and 75% respectively) and substantial morbidity in survivors. Recent research suggests that IA and AAA share genetic risk in addition to environmental factors. Retrospective data from our institution identified a population harboring both IA and AAA and showed a high rupture rate for IA (44.2%). We previously demonstrated that screening for AAA in patients with IA is cost-effective based on estimated and published data. We hypothesize that screening for IA in patients with AAA is also cost-effective. Method: We developed a decision-making model using TreeAge Pro 2013 software assuming a hypothetical population with known AAA and truncated screening versus no screening for IA using magnetic resonance angiography. Based on IA size and location, patients were either treated endovascularly or placed on surveillance. Proportions, risks, utilities, and costs for each decision arm were derived from literature. Results: At a given rupture rate, incremental effectiveness varied linearly with coprevalence of AAA and IA. For an assumed rupture rate of 5%/year, screening was effective for coprevalence >6.8% (top graph) and was cost-effective for coprevalence >7.7%. The incremental cost-effectiveness ratio (ICER) favored screening (ICER=$54,193/QALY) at a 7.8% coprevalence and dropped to $27,841.50/QALY at 8.8% coprevalence. Our model was sensitive to IA rupture rate as well as coprevalence (bottom graph). Conclusion: Our model suggests the cost-effectiveness of screening for IA in patients with AAA, below the accepted societal threshold of an ICER $60,000/QALY at a coprevalence ≥7.8% and IA rupture rate ≥5%. These are plausible assumptions for this genetically high-risk population. Further prospective study is warranted to establish coprevalence of AAA and IA, rupture rates, and determine the benefit of dedicated screening.