Hypertension differences among blacks in two middle-income countries: dominica and the Seychelles.

The prevalence of hypertension (HT) varies greatly between Black populations in the world. It is high among African-Americans, but relatively low among tribal groups in both East and West Africa. Descendants of East Africa and West African Blacks are found in the island countries of the Seychelles (Indian Ocean) and Dominica (Caribbean sea) respectively. Both islands have populations of about 75,000. The World Bank classifies each as a “middle-income country”, although the Seychelles has a higher per capita income ($6,000 v $2,360). The epidemiology of HT in both countries was compared by pooling data from the Seychelles (SEY) Heart Study and the Dominica (DOM) Rapid Epidemiological Survey. Because “modernization” is often associated with hypertension, we hypothesized that SEY would have a higher prevalence of the disease. A random sample of black men and women aged 25-64 years were chosen in both countries (n=153 in DOM and N=714 in SEY). The crude prevalence of HT (WHO definition) was 20% in DOM and 37% in SEY. Using regression modeling to adjust for differences in the age and sex distribution, SEY had greater odds of having HT (OR=1.83, p<.008). To assess potential underlying mechanisms, we adjusted for factors associated with modernization: alcohol use, tobacco use, high body mass index, low education level, however, this did not appreciably affect the age and sex adjusted results. We conclude that either environmental risk factors not accounted for here or genetic differences (due to intra-racial factors or admixture) between the two populations are responsible for the greater prevalence of HT in Seychelles when compared to Dominica.