Cost-effectiveness of screening for asymptomatic carotid stenosis.
OBJECTIVE
The benefit of carotid endarterectomy for patients who are asymptomatic with > 60% carotid stenosis has been established by the Asymptomatic Carotid Atherosclerosis Study (ACAS). Which screening strategy is most appropriate is still unclear. This study assessed the cost-effectiveness of ultrasound screening for asymptomatic carotid stenosis.


METHODS
Cost-effectiveness analysis was performed with a Markov model and with data from ACAS and other studies.


RESULTS
For 60-year-old patients with a 5% prevalence of 60% to 99% asymptomatic stenosis, duplex ultrasound screening increased average quality-adjusted life years (QALY; 11.485 vs 11.473) and lifetime cost of care ($5500 vs $5012) under base-case assumptions. The incremental cost per QALY gained (cost-effectiveness ratio) was $39,495. Screening was cost-effective with the following conditions: disease prevalence was 4.5% or more, the specificity of the screening test (ultrasound) was 91% or more, the stroke rate of patients who were medically treated was 3.3% or more, the relative risk reduction of surgery was 37% or more, the stroke rate associated with surgery was 160% or less than that of the North American Symptomatic Carotid Endarterectomy Trial or ACAS perioperative complication rates, and the cost of ultrasound screening was $300 or less. A one-time screening, compared with a screening every 5 years, had more QALY (11.485 vs 11.482) and lower cost ($5500 vs $5790). Screening without arteriography, compared with screening with arteriographic verification, provided few additional QALYs (11.486 vs 11.485) at additional cost ($6896 vs $5500). The cost-effectiveness ratio was sensitive to assumptions about the stroke rate of patients who were asymptomatic and other variables.


CONCLUSIONS
Screening for asymptomatic carotid stenosis can be cost-effective when both screening and carotid endarterectomy are performed in centers of excellence.
Yin
D
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Leonard Davis Institute of Health Economics, University of Pennsylvania School of Medicine, Philadelphia, USA.
Carpenter
J P
JP
D016893:Carotid Stenosis / Q000191:economics* / Q000453:epidemiology / Q000517:prevention & control*; D002533:Cerebral Angiography / Q000191:economics; D002561:Cerebrovascular Disorders / Q000517:prevention & control; D003362:Cost-Benefit Analysis; D003661:Decision Support Techniques; D016894:Endarterectomy, Carotid / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008297:Male; D008390:Markov Chains; D008403:Mass Screening / Q000191:economics* / Q000379:methods; D008875:Middle Aged; D015995:Prevalence; D019057:Quality-Adjusted Life Years; D018570:Risk Assessment; D012680:Sensitivity and Specificity; D018616:Ultrasonography, Doppler, Duplex / Q000191:economics*; D014481:United States