Five Year Outcomes in Men Screened for Carotid Artery Stenosis at 65 Years of Age: A Population Based Cohort Study.

OBJECTIVE: This study aimed to determine the outcome of 65 year old men five years after carotid ultrasound screening, as well as risk factors for disease progression. METHODS: All 65 year old men living in the county of Uppsala 2007-2009 were invited to an ultrasound examination of both carotid arteries and re-invited at age 70. The cohort was grouped into normal carotids, plaque without significant stenosis, moderate stenosis (50-79%), and severe stenosis (80-99%). The rate of disease progression was assessed from ultrasound data. Data on mortality, ipsilateral neurological events, risk factors, and medication were obtained from patient records and population registries. RESULTS: Among men participating in carotid screening at age 65, 3,057 were re-screened at age 70. In those with normal carotids (n = 2,318), 23 (1.0%) progressed to a moderate stenosis, and four (0.2%) to a symptomatic severe stenosis. Among those with plaque (n = 696), 25 (3.6%) progressed to moderate stenosis, and eight (1.1%) to severe stenosis, of whom four (0.6%) had symptoms. Of 31 men with 50-79% stenosis, four (12.9%) had progressed to a severe stenosis, of whom two (6.5%) developed symptoms. Five of twelve subjects (42%) with 80-99% stenosis developed symptoms. Disease regression was present among 289/692 plaque (41.7%) and 16/33 stenosis (48.4%). In multivariable analysis, smoking, coronary artery disease and hypercholesterolemia were associated with disease progression. The proportions of antiplatelet, statin, and antihypertensive treatment in the population at age 70 were 22%, 29%, and 55%, respectively. CONCLUSION: Men with plaques and moderate stenosis have a good prognosis, but in those with severe stenosis there is a high risk of neurological events.

Clinical Effect and Cost-Effectiveness of Screening for Asymptomatic Carotid Stenosis: A Markov Model.

OBJECTIVE/BACKGROUND: The cost-effectiveness of screening depends on the cost of screening, prevalence of asymptomatic carotid artery stenosis (ACAS), and the potential effect of medical intervention in reducing the risk of stroke. The aim of the study was to determine the threshold values for these parameters in order for screening for ACAS to be cost-effective. METHODS: The clinical effect and cost-effectiveness of ultrasound screening for ACAS with subsequent initiation of preventive therapy versus not screening was assessed in a Markov model with a lifetime perspective. Key parameters, including stroke risk, all cause mortality, and costs, were based on contemporary published data, population statistics, and data from an ongoing screening program in Uppsala county (population 300,000), Sweden. Prevalence of ACAS (2%) and the rate of best medical treatment (BMT; 40%) were based on data from a male Swedish population recently screened for ACAS. The required stroke risk reduction from BMT, incremental cost-efficiency ratio (ICER), absolute risk reduction for stroke (ARR), and number needed to screen (NNS) were calculated. RESULTS: Screening was cost-effective at an ICER of €5744 per incremental quality adjusted life year (QALY) gained. ARR was 135 per 100,000 screened, NNS was 741, and QALYs gained were 6700 per 100,000 invited. At a willingness to pay (WTP) threshold of €50,000 per QALY the minimum required stroke risk reduction from BMT was 22%. The assumed degree of stroke risk reduction was the most important determinant of cost-efficiency. CONCLUSION: A moderate (22%) reduction in the risk of stroke was required for an ACAS screening strategy to be cost-effective at a WTP of €50,000/QALY. Targeting populations with a higher prevalence of ACAS could further improve cost-efficiency.

Simplified ultrasound protocol for the exclusion of clinically significant carotid artery stenosis.

OBJECTIVES: To evaluate a simplified ultrasound protocol for the exclusion of clinically significant carotid artery stenosis for screening purposes. MATERIAL AND METHODS: A total of 9,493 carotid arteries in 4,748 persons underwent carotid ultrasound examination. Most subjects were 65-year-old men attending screening for abdominal aortic aneurysm. The presence of a stenosis on B-mode and/or a mosaic pattern in post-stenotic areas on colour Doppler and maximum peak systolic velocity (PSV) in the internal carotid artery (ICA) were recorded. A carotid stenosis was defined as The North American Symptomatic Carotid Endarterectomy Trial (NASCET) >20% and a significant stenosis as NASCET >50%. The kappa (κ) statistic was used to assess agreement between methods. Sensitivity, specificity, positive predictive (PPV), and negative predictive (NPV) values were calculated for the greyscale/mosaic method compared to conventional assessment by means of PSV measurement. RESULTS: An ICA stenosis was found in 121 (1.3%) arteries; 82 (0.9%) were graded 20%-49%, 16 (0.2%) were 50%-69%, and 23 (0.2%) were 70%-99%. Eighteen (0.2%) arteries were occluded. Overall, the greyscale/mosaic protocol showed a moderate agreement with ICA PSV measurements for the detection of carotid artery stenosis, κ = 0.455. The sensitivity, specificity, PPV, and NPV for detection of >20% ICA stenosis were 91% (95% CI 0.84-0.95), 97% (0.97-0.98), 31% (0.26-0.36), and 97% (0.97-0.97), respectively. The corresponding figures for >50% stenosis were 90% (0.83-0.95), 97% (0.97-0.98), 11% (0.08-0.15), and 100% (0.99-1.00). CONCLUSION: Compared with PSV measurements, the simplified greyscale/mosaic protocol had a high negative predictive value for detection of >50% carotid stenosis, suggesting that it may be suitable as a screening method to exclude significant disease.