Suspected Carotid Artery Stenosis: Cost-effectiveness of CT Angiography in Work-up of Patients with Recent TIA or Minor Ischemic Stroke

Abstract

To assess the effectiveness and cost-effectiveness of state-of-the-art noninvasive diagnostic imaging strategies in patients with a transient ischemic attack (TIA) or minor stroke who are suspected of having carotid artery stenosis (CAS). All prospectively evaluated patients provided informed consent, and the local ethics committee approved this study. Diagnostic performance, treatment, long-term events, quality of life, and costs resulting from strategies employing duplex ultrasonography (US), computed tomographic (CT) angiography, contrast material-enhanced magnetic resonance (MR) angiography, and combinations of these modalities were modeled in a decision tree and Markov model. Data sources included a prospective diagnostic cohort study, a meta-analysis, and a review of the literature. Outcomes were costs, quality-adjusted life-years (QALYs), incremental cost-effectiveness ratios, and net health benefits (QALY-equivalents), with a willingness-to-pay threshold of euro 50,000 per QALY and a societal perspective. The strategy with the highest net health benefit was considered the most cost effective. Extensive one-way, two-way, and probabilistic sensitivity analyses to explore the effect of varying parameter values were performed. The reference case analysis assumed that patients underwent surgery 2-4 weeks after the first symptoms, and the effect of earlier intervention was explored. The reference case analysis showed that duplex US combined with CT angiography and surgery for 70%-99% stenoses was the most cost-effective strategy, with a net health benefit of 13.587 and 15.542 QALY-equivalents in men and women, respectively. In men, the CT angiography strategy with a 70%-99% cutoff yielded slightly more QALYs, at an incremental cost of euro 71,419 per QALY, compared with duplex US combined with CT angiography. In patients with a high-risk profile, in patients with a high prior probability of disease, and when patients could be treated within 2 weeks after the first symptoms, the CT angiography strategy with surgery for 50%-99% stenoses was the most cost-effective strategy. In diagnosing CAS, duplex US should be the initial test, and, if its results are positive, CT angiography should be performed; patients with 70%-99% stenoses should then undergo carotid endarterectomy. In patients with a high-risk profile, a high probability of CAS, or who can undergo surgery without delay, immediate CT angiography and surgery for 50%-99% stenoses is indicated.