Background: Carotid artery stenosis (50-99% extracranial internal carotid artery narrowing) is a risk factor for ischemic stroke. However, no population-based studies have directly assessed the benefits and harms of screening for asymptomatic carotid artery stenosis (ACAS), and the CREST-2 trial is currently evaluating the efficacy of revascularization vs. intensive medical management for ACAS patients. Given this gap, the United States Preventive Services Task Force (USPSTF) currently recommends against screening for ACAS in the general population. Because ACAS prevalence and ischemic stroke risk vary by clinical risk factors, we sought to quantify the cost-effectiveness of screening for ACAS by cardiovascular disease risk-based sub-groups. Methods: We developed a microsimulation model of ACAS and stroke to project the lifetime costs and quality-adjusted life-years (QALYs) associated with ACAS screening, stratified by individuals' 10-year atherosclerotic cardiovascular disease (ASCVD) risk. We used individual-level data to estimate probabilities and severity of ACAS based on individual characteristics (e.g., age, sex, smoking status, blood pressure, and cholesterol). Annual stroke risks were functions of these characteristics and the degree of ACAS. In the model, individuals testing positive with Duplex ultrasound (>70% stenosis) and a confirmatory diagnostic test undergo revascularization, which reduces the risk of stroke but also introduces risk of complications. Diagnostic performance parameters, revascularization benefits and risks, and costs were estimated from published sources. Cost-effectiveness was assessed using a $100,000/QALY willingness-to-pay threshold. Results: Compared to no screening, the incremental value of a one-time screening for adults aged 50-80 varied by ASCVD risk. Screening adults with 10-year ASCVD risk >30% and >25% resulted in incremental cost-effectiveness ratios of $29,500/QALY and $73,600/QALY, respectively. Screening strategies for adults with ASCVD risk thresholds lower than 25% were not cost-effective at the $100,000/QALY threshold. Results were sensitive to variation in the risks and benefits associated with revascularization. Conclusions: Although the USPSTF recommends against screening for ACAS in the general population, a one-time screen may be cost-effective for adults aged 50+ with ASCVD risk >25%. Depending on updated findings from CREST-2, ACAS screening may still be cost-effective for higher ASCVD risk thresholds, even with lower efficacy or higher risks of revascularization than our base-case estimates.

The authors have declared no competing interest.

Dr. Pandya was supported by funding from the National Institute of Neurological Disorders and Stroke (R01NS104143).

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