The prevalence of carotid artery stenosis varies significantly by race

Abstract

Objective: Certain races are known to be at increased risk for stroke, and the prevalence of carotid artery stenosis (CAS) is thought to vary by race. The goal of this report was to study the prevalence of CAS in different races by analyzing a population of subjects who underwent vascular screening examinations.

Methods: The study data were provided by Life Line Screening. The cohort consists of self-referred individuals who paid for vascular screening tests. Subjects <40 and >100 years of age and those who reported a prior stroke or carotid artery intervention were excluded. Of the remaining 3,291,382 subjects, 3.7% did not self-identify a race. CAS was defined as stenosis in either internal carotid artery ≥50% by duplex ultrasound velocity criteria.

Results: The 3,291,382 subjects available for analysis consisted of Caucasian (2,845,936 [90%]), African American (97,502 [3.1%]), Hispanic (75,240 [2.4%]), Asian (60,982 [1.9%]), and Native American (87,757 [2.8%]) individuals. The prevalence of CAS was 3.4% in females and 4.2% in males (P ≤ .001). Controlling for gender and age, there was marked variation in the prevalence of CAS (P < .001) by race. Native American subjects had the highest prevalence of CAS across all age categories and in both sexes. Caucasian subjects had the second highest prevalence of CAS across most age decades and in both sexes. Among males, African American individuals had the lowest prevalence of CAS in nearly all age categories. In contrast to males, Asian females had the lowest prevalence of CAS compared with females of other races in most age groups. Multivariate analysis adjusting for atherosclerotic risk factors in addition to age confirmed race as a significant independent predictor of CAS. Compared with Caucasian subjects, African American (odds ratio [OR], 0.65), Asian (OR, 0.69), and Hispanic (OR, 0.74) subjects had a significantly lower risk of CAS, whereas Native American (OR, 1.3) subjects had a significantly higher risk of CAS.

Conclusions: The prevalence of clinically significant CAS varies significantly by race. Native American and Caucasian individuals have the highest prevalence of CAS, whereas African American males and Asian females appear to have the lowest prevalence. This information adds evidence to the hypothesis that the increased stroke rate in African American subjects is likely not related to extracranial cerebrovascular disease. Furthermore, this is a novel report of an extremely high prevalence of CAS in the Native American population.