Metabolic syndrome and coronary heart disease in South Asians, African-Caribbeans and white Europeans: a UK population-based cross-sectional study

Abstract

Aims/hypothesis: The aim of this study was to study differences in the prevalence of the metabolic syndrome and its associations with prevalent CHD according to ethnicity and sex. Methods: We performed a combined analysis of two population-based cross-sectional studies conducted between 1988 and 1991 that followed identical protocols. Participants (aged 40-69 years) comprised 2,346 Europeans (76% male), 1,711 South Asians (83% male) and 803 African-Caribbeans (57% male) resident in west London. Fasting blood, overnight urine collection, clinical and anthropometric measurements were performed. Clinical history or major ECG changes defined prevalent CHD. The metabolic syndrome was defined according to the criteria recommended by the World Health Organization (WHO) and the National Cholesterol Education Programme (NCEP). Results: The prevalence of the metabolic syndrome was highest in South Asians (WHO, men 46%, women 31%; NCEP, men 29%, women 32%) and lowest in European women (WHO, 9%; NCEP, 14%). The prevalence of CHD was 10% in South Asian men, 9% in European men, 5-6% in African-Caribbeans and European women, and 2% in South Asian women. The metabolic syndrome was associated with prevalent CHD in European men [NCEP, odds ratio (OR)=1.6, 95% CI 1.2-2.4; WHO, OR=1.7, 95% CI 1.2-2.5] and South Asian men (NCEP, OR=2.1, 95% CI 1.5-3.1; WHO, OR=1.6, 95% CI 1.1-2.3). Associations with CHD were weaker in African-Caribbeans and were inconsistent among European women. Conclusions/ interpretation: The current definitions of the metabolic syndrome give an inconsistent picture of cardiovascular disease risk when applied to different ethnic groups within the UK. Prospective studies are needed to validate workable ethnic-specific definitions.

Ethnicity modifies the association between diabetes mellitus and ischaemic heart disease in Chinese, Malays and Asian Indians living in Singapore

“…This finding is in accordance with previous findings [11,[15][16][17][18][19][20][21]. As in previous studies, adjustment for other traditional risk factors did not entirely account for the increased risk of IHD in this ethnic group [11,19].…”

Type 2 diabetes and cardiovascular risk in the UK south Asian community

“…When grouped together, they are associated with an increased risk of cardiovascular disease, and clustering of the metabolic syndrome components is frequently seen in south Asians [70]. The prevalence of the above risk factors in patients of south Asian extraction suggests they have a particular propensity to develop the metabolic syndrome [71] (Fig. 5), which may explain, at least in part, their increased risk of type 2 diabetes and cardiovascular disease.…”

“…Although it is unlikely that distinct genetic factors underlie the inherited risk of type 2 diabetes and CHD in south Asians compared with Caucasians, there may be a higher prevalence of some risk alleles in specific ethnic groups. An example of an allele that may contribute to insulin resistance in south Asians is a polymorphism in the [71] gene encoding plasma cell membrane glycoprotein-1 (PC-1), which affects insulin signalling by direct interaction with the alpha subunit of the insulin receptor, blocking insulin action. The PC-1 K121Q polymorphism has been associated with a stronger inhibitory effect on the insulin receptor than the wild-type, and occurs with a significantly higher frequency in south Asians compared with Caucasians (33 vs 26%, respectively) [75].…”

Hypertension as part of the metabolic syndrome

“…6,7 In Britain, it is around 20-30%. 8 Its prevalence increases with age and exceeds 40% in the elderly. Although the metabolic syndrome is a newly defined disease, 9,10 its importance is increasingly recognized because it predicts cardiovascular disease and the development of diabetes.…”