Prevalence of Asymptomatic Carotid Artery Stenosis According to Age and Sex

BACKGROUND AND PURPOSE: In the discussion on the value of population-wide screening for asymptomatic carotid artery stenosis (ACAS), reliable prevalence estimates are crucial. We set out to provide reliable age- and sex-specific prevalence estimates of ACAS through a systematic literature review and meta-regression analysis. METHODS: We searched PubMed and EmBase until December 2007 for studies that reported the prevalence of ACAS in a population free of symptomatic carotid artery disease. Data were extracted with use of a standardized form on participants' characteristics, assessment method, study quality, and prevalence estimates for moderate (>or=50% stenosis) and severe (>or=70% stenosis) ACAS. Metaregression was used to investigate sources of heterogeneity. RESULTS: Forty studies fulfilled the inclusion criteria. There was considerable variation among studies with respect to demographics, methods of grading stenosis, and stenosis cutoff point used. The pooled prevalence of moderate stenosis was 4.2% (95% CI, 3.1% to 5.7%). Prevalence of moderate stenosis among people age or=70 years, prevalence increased to 12.5% (95% CI, 7.4% to 20.3%) in men and to 6.9% (95% CI, 4.0% to 11.5%) in women. Metaregression showed that both age and sex significantly affected the prevalence of moderate stenosis. No contribution of study size, publication year, geographic region, assessment method, and study quality was found. The pooled prevalence of severe stenosis was 1.7% (95% CI, 0.7% to 3.9%). CONCLUSIONS: Prevalence of moderate stenosis increases with age in both men and women, but men at all ages have the higher prevalence estimates. The number of studies that allowed meaningful data synthesis of severe stenosis was limited.