Nurose Karim, MD
Why is there less carotid revascularization in African American and Hispanic populations despite them having greater cardiovascular risk factors? Is this due to disparities in the access to care? Or it is truly due to low incidence of severe carotid stenosis (defined as the peak systolic velocity >230 cm/sec on carotid ultrasound)? While American Heart Association and United States Preventive Services Taskforce (USPSTF) recommendations do not support the carotid screening of the general population, Life Line Screening (LLS, Independence, Ohio) is a direct-to-consumer company in which individuals can self-pay for vascular assessments if they choose.
The authors collected data from LLS for all the patients who underwent screening for carotid stenosis from 2005-2019. Data was stratified on the basis of race/ethnicity (White, Black, Hispanic, Asian, Native American or other), sex (men or women), and age (45-54, 55-64, 65-74 or 75-84 years). Patients above age 85 were excluded. This led to a total of 6,130,481 unique participants. The prevalence of high-grade carotid stenosis was significantly lower for Black, Hispanic and Asian individuals compared to White individuals. This is comparable with the data from the 2015 census for population with high-grade stenosis and reported the prevalence as 72% of the White population, with Black and Hispanic populations comprising 11% each, and women comprising 52%.
This is the first study to address race/ethnic differences in the prevalence of high-grade stenosis in the general population. There were some concerns that the LLS population might not be the true representation of the United States population due to the LLS cohort being self-referred, differences in financial resources available for self-pay, LLS testing locations with low proportions of Black and Hispanic individuals, and other barriers to testing that could introduce racial bias. But actually, the Black-White prevalence ratios for major risk factors in the LLS cohort were quite similar to other published studies like REGARDS.
This study made three important conclusions:
1) A lower prevalence of high-grade carotid stenosis in both Black and Hispanic individuals relative to White individuals.
2) A relatively heavier risk factor burden (hypertension and diabetes) for Black individuals than for White individuals. Specifically, there was a substantially higher prevalence of hypertension and diabetes in Black individuals than White individuals.
3) A very similar prevalence of dyslipidemia in Black and White individuals (only a 0.8% difference).
Unfortunately, smoking data was missing in the majority of the population in the cohort. For the data available, there was only a marginally higher prevalence of smoking in White individuals than Black individuals (6.6% higher in White individuals). For the completeness of the study, a sensitivity analysis was performed assessing the impact of risk factor adjustment on the estimated prevalence ratio for high-grade stenosis in the 2,791,017 participants with complete risk factor data (including smoking). It showed that the adjustment of these risk factors had virtually no impact on the estimated racial differences in the prevalence of high-grade stenosis. The strength of this study is that LLS is not drawn from a hospital/clinical population, and it offers the opportunity to assess racial differences in the prevalence of high-grade stenosis in the general population.