Search

A ten-year community survey was undertaken to investigate the high coronary heart disease (CHD) incidence among people of Indian (South Asian) descent in Trinidad, West Indies. Of 2491 individuals aged 35-69 years, 2215 (89%) were examined and 2069 (83%) found to be clinically free of CHD at baseline. After exclusion of 71 of minority ethnic groups, 786 African, 598 Indian, 147 European and 467 adults of Mixed descent were followed for CHD morbidity and mortality. In both sexes, adults of Indian origin had higher prevalence rates of diabetes mellitus, a low concentration of high-density lipoprotein (HDL) cholesterol, and recent abstinence from alcohol than other ethnic groups. Indian men also had larger skinfold thicknesses than other men. In participants free of CHD at entry, the age-adjusted relative risk of a cardiac event believed due to CHD was at least twice as high in Indian men and women as in other ethnic groups. In men, blood pressure, diabetes mellitus and low-density lipoprotein (LDL) cholesterol concentration were positively and independently related to risk of CHD, whereas alcohol consumption and HDL cholesterol concentration were inversely associated with risk after allowing for age and ethnic group. The ethnic contrasts in CHD persisted when these characteristics were taken into account. In the smaller sample of women, only ethnic group was predictive of CHD as defined. The failure of point estimates of risk to explain the high CHD incidence in Indians calls for focus on age of onset of risk and examination of other potential risk factors such as insulin concentration.

A prospective survey has been undertaken of a total community of 1343 men and 1149 women, aged 35-69 years at recruitment, living in Port-of-Spain, Trinidad. By comparison with adults of African descent, age-adjusted relative risks of death from all causes and from cardiovascular diseases were significantly increased in those of Indian origin (1·5 and 2·6, respectively) and reduced in those of mixed descent (0·5 and 0·3, respectively). Adults of European descent had an all-cause and cardiovascular mortality relative risk of 0·8 and 2·1, respectively. These ethnic differences in risk were not explained by systolic blood pressure, fasting blood glucose concentration, serum high-density lipoprotein or low-density lipoprotein concentration, or smoking habits. Differences in risk of cardiovascular death between Indian and European men seemed to be accounted for by the high prevalence of diabetes in Indians (19%) but other ethnic contrasts in mortality were unrelated to diabetes mellitus.

A total population survey of serum lipoprotein concentrations was undertaken in an urban community in Port-of-Spain, Trinidad, and the results compared with rural survey on the same island and a study of healthy adults in Bristol, England. Lipoproteins were separated with identical techniques and lipid determinations made in a common laboratory. In Trinidad, response rates for men and women were 93 and 88% respectively in the urban survey, and 89% in the smaller rural study. Mean concentration of HDL cholesterol was significantly lower and LDL cholesterol significantly higher in urban men than rural men. No urban-rural differences were found in women. In urban men under 55 years, HDL and LDL cholesterol concentrations were similar in Port-of-Spain and Bristol while VLDL triglyceride was relatively high in Trinidad. Distinct ethnic differences in lipoprotein concentrations were found in Trinidad. Indian men and women tended to have a low HDL cholesterol relative to other ethnic groups, while African men and women were characterized by relatively low concentrations of LDL cholesterol and VLDL triglyceride. The reduction in HDL cholesterol of Indian men appeared to be due mainly to a relatively low HDL3 concentration. The results are consistent with reported regional, sex and ethnic differences in CHD incidence in Trinidad, and accord with statistics which show cardiovascular disease to have emerged as the major cause of death in this community.

In a prospective survey of 1342 Trinidadian men aged 35 to 69 years at recruitment, age-adjusted mean blood pressures were highest in those of African descent, intermediate in Indians and mean of Mixed origin, and lowest in Europeans. Age-adjusted fasting blood glucose concentrations were highest in Indians and lowest in men of European descent. Relative risks of all-cause, cardiovascular and cerebrovascular mortality increased progressively with increasing systolic pressure, whereas for fasting blood glucose concentration the associations were U-shaped. No ethnic differences were apparent in relative risks. For systolic pressure, mortality from all-causes and cardiovascular diseases respectively were about two and three times higher at 180 mmHg or more than at pressures below 130 mmHg. For blood glucose, all-cause and cardiovascular mortality were about four times higher at fasting concentrations greater than 7.7 mmol/l than in the lowest risk group (4.2-4.6 mmol/l). All-cause population attributable mortality rates for systolic pressures of 130 mmHg or more were 1.3 to 2.8 times higher in Indian men than in other groups. For blood glucose in excess of 4.6 mmol/l, population attributable mortality was between 2.9 and 6.9 times higher in Indians than in other groups. The findings emphasized the high mortality in men of Indian descent, partly due to an apparent underlying predisposition to cardiovascular disease, and partly to their high prevalence of diabetes mellitus.