Paradoxical ethnic differences in prevalence of vascular risk factors versus extracranial atherosclerotic disease in TIA/stroke patients in the United Kingdom: Population-based study and meta-analysis

Background Studies in Northern America report a lower prevalence of coronary artery disease (CAD) in Black than White people despite higher prevalence of vascular risk factors. However, it remains unclear to what extent these differences are driven by biology or reflect ethnic disparities in smoking, socioeconomic deprivation, healthcare access, and health-seeking behaviour. We aimed to determine if ethnic differences in coronary and peripheral artery disease persist in people with stroke living in the United Kingdom (UK), considering that most people with stroke seek medical attention and the National Health Service provides equitable access to care. Methods In a prospective population-based cohort of all patients with suspected TIA or stroke in Oxfordshire, UK (Oxford Vascular Study, OxVasc, April 2002 to March 2023), we fitted multivariable logistic regression models to quantify the association of ethnicity and extracranial atherosclerotic disease (coronary or peripheral) while adjusting for age, sex, vascular risk factors, and socioeconomic deprivation. We verified our findings in a systematic review of UK-based studies reporting prevalence of extracranial atherosclerotic disease and associated vascular risk factors across ethnic groups. Prevalence estimates were pooled by random-effects meta-analysis. Results In 7297 OxVasc participants (52.6% women, 71.0 ± 15.5 years), non-White people ( n = 335) had a higher prevalence of diabetes mellitus (OR = 3.26, 2.55–4.16). However, Black people had a lower prevalence of CAD (OR = 0.31, 0.10–0.98, p = 0.046) or any extracranial atherosclerotic disease (OR = 0.42, 0.18–0.96, p = 0.04) than White people. After adjustment for age, sex, vascular risk factors, and deprivation, the difference was attenuated both for CAD (aOR = 0.50, 0.18–1.41, p = 0.19) and any extracranial atherosclerotic disease (aOR = 0.43, 0.18–1.04, p = 0.06). Asian and White people had similar prevalence of CAD and extracranial atherosclerotic disease. Among UK-based studies of patients with stroke, Black and Asian people were more likely than White people to have diabetes (pooled OR: 2.78, 2.40–3.22, n = 3 studies; 4.15, 3.11–5.53 n = 6), hypertension (1.95, 1.47–2.60, n = 3; 1.47, 1.02–2.12, n = 6), and obesity (1.52, 1.27–1.83, n = 1; 1.2, 0.66–2.29, n = 3) but less likely to be smoking (0.70, 0.50–0.97, n = 2; 0.57, 0.44–0.74, n = 5). Yet, Black people had less CAD than White (0.48, 0.31–0.76, n = 3) and Asian (0.30, 0.10–0.80, n = 2) people. Interpretation We confirm the existence of a coronary artery disease paradox in Black but not Asian people with TIA or stroke, which is likely independent of biases in healthcare access or health-seeking behaviour, and may suggest different biological susceptibilities.