Cost-effectiveness of screening for carotid stenosis in asymptomatic persons

Background: The Asymptomatic Carotid Atherosclerosis Study (ACAS) showed that carotid endarterectomy was beneficial for symptom-free patients with carotid stenosis of 60% or more. This finding raises the question of whether widespread screening to identify cases of asymptomatic carotid stenosis should be implemented. Objective: To determine whether a screening program to identify cases of asymptomatic carotid stenosis would be a cost-effective strategy for stroke prevention. Design: Cost-effectiveness analysis using published data from clinical trials. Setting: General population of asymptomatic 65-year-old men. Intervention: Patients who were screened for carotid disease with duplex Doppler ultrasonography were compared with patients who were not screened. If ultrasonography found significant carotid stenosis (greater than or equal to 60%), disease was confirmed by angiography before carotid endarterectomy was done. Measurements: Quality-adjusted life-years, costs, and marginal cost-effectiveness ratios. Results: When the conditions and results of ACAS were modeled and it was assumed that the survival advantage produced by endarterectomy would last for 30 years, the lifetime marginal cost-effectiveness of screening relative to no screening was $120 000 per quality-adjusted life-year. Sensitivity analysis showed that marginal cost-effectiveness decreased to $50 000 or less per quality-adjusted life-year only under implausible conditions (for example, if a free screening instrument with perfect test characteristics was used or an asymptomatic population with a 40% prevalence of carotid stenosis was found). Conclusions: Surgery offers a real but modest absolute reduction in the rate of stroke at a substantial cost. A program to identify candidates for endarterectomy by screening asymptomatic populations for carotid stenosis costs more per quality-adjusted life-year than is usually considered acceptable.