Sex and ethnicity differences in coronary heart disease: A UK-based tri-ethnic cohort analysis

Background and aims: Sex differences in ethnic minority risk of coronary heart disease (CHD) are often overlooked. Here we aim to explore sex-by-ethnicity differences in CHD outcomes and the contribution of risk factors. Methods: Incident CHD events were identified for Europeans, and South Asian and African/African Caribbean first generation migrants in the UK-based Southall and Brent Revisited (SABRE) cohort. Cardiovascular risk factors were assessed at baseline (1988-91). Cox proportional hazards models quantified group differences in CHD incidence and risk factor contribution. Population attributable fractions (PAFs) described risk factor contribution to group differences. Results: Among 4,754 participants followed for 40.8 years, 1,710 CHD first events occurred. Cumulative incidence of CHD was highest in South Asian males (65% by age 90) and females (55%), compared with 52% in European males and 24-31% in other groups. Sex differences in CHD incidence were pronounced in Europeans (female versus male HR=0.45, 95% CI [0.37,0.55]) but attenuated in South Asians (0.68 [0.56,0.82]) and African/African Caribbeans (0.79 [0.57,1.10]). CHD risk was higher in South Asian compared to European men (1.80 [1.63,1.99]). This ethnic difference was greater in females (2.44 [1.88,3.17]). PAFs for diabetes (PAF=18.0%, 95% CI [6.2,29.8]), hypercholesterolemia (44.2% [20.4,68.1]), and hypertriglyceridemia (22.4% [7.9,37.0]) made a greater contribution to the risk of CHD in South Asian females compared to all other groups. Conclusions: Ethnic minority female participants do not have the same protection from CHD as Europeans. Greater cardiometabolic burden may drive this elevated CHD risk and loss of female protection.