Hypertension: effects of social class and racial admixture: the results of a cohort study in the black population of Charleston, South Carolina.

It has been hypothesized that genetic factors, as manifested by skin color, play in important role in the genesis of hypertension among Blacks. A community-based study was carried out in Charleston Country, South Carolina to test this hypothesis. The results of a ten year follow-up study suggest that social class and age were more consistently associated with the incidence of hypertension and levels of blood pressure. The association of hypertension with skin color was minimal and substantially less than that of social class. The incidence rate of hypertension (larger than or equal to 90 mm Hg) was three to four times greater when the study participants were of low social class than when they had higher social class scores at the beginning of this study. In contrast, the incidence rate was only 1.5 times higher for dark than for lighter skinned men, and the rates were almost identical when social class was comparable. Similar results energed when blood pressure was treated as a continuous variable; blood pressure levels and pressure changes over time were consistently and significantly (p less than .01) higher in those Blacks categorized as low social class, controlling for skin color.