OBJECTIVES: This study was undertaken to describe the distribution of blood pressures, hypertension prevalence, and associated risk factors among seven populations of West African origin. METHODS: The rates of hypertension in West Africa (Nigeria and Cameroon), the Caribbean (Jamaica, St. Lucia, Barbados), and the United States (metropolitan Chicago, Illinois) were compared on the basis of a highly standardized collaborative protocol. After researchers were given central training in survey methods, population-based samples of 800 to 2500 adults over the age of 25 were examined in seven sites, yielding a total sample of 10014. RESULTS: A consistent gradient of hypertension prevalence was observed, rising from 16% in West Africa to 26% in the Caribbean and 33% in the United States. Mean blood pressures were similar among persons aged 25 to 34, while the increase in hypertension prevalence with age was twice as steep in the United States as in Africa. Environmental factors, most notably obesity and the intake of sodium and potassium, varied consistently with disease prevalence across regions. CONCLUSION: The findings demonstrate the determining role of social conditions in the evolution of hypertension risk in these populations.

OBJECTIVE -Rates of non-insulin-dependent diabetes mellitus have risen sharply in recent years among blacks in the U.S. and the U.K. Increases in risk have likewise been observed in the island nations of the Caribbean and in urban West Africa. To date, however, no systematic comparison of the geographic variation of NIDDM among black populations has been undertaken. RESEARCH DESIGN AND METHODS-In the course of an international collaborative study on cardiovascular disease, we used a standardized protocol to determine the rates of NIDDM and associated risk factors in populations of the African diaspora. Representative samples were drawn from sites in Nigeria, St. Lucia, Barbados, Jamaica, the United States, and the United Kingdom. A total of 4,823 individuals aged 25-74 years were recruited, all sites combined.RESULTS -In sharp contrast to a prevalence of 2% in Nigeria, age-adjusted prevalences of self-reported NIDDM were 9% in the Caribbean and 11% in the U.S. and the U.K. Mean BMI ranged from 22 kg/m 2 among men in West Africa to 31 kg/m 2 in women in the U.S. Disease prevalence across sites was essentially collinear with obesity, pointing to site differences in the balance between energy intake and expenditure as the primary determinant of differential NIDDM risk among these populations.CONCLUSIONS -In ethnic groups sharing a common genetic ancestry, these comparative data demonstrate the determining influence of changes in living conditions on the population risk of NIDDM.

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Background and Purpose-Estimation of stroke incidence among black populations outside the USA and the UK has been hampered by the lack of community-based studies. We aimed to document the incidence of first-ever stroke in Barbados, a Caribbean island with a population of 268 000 people. Methods-A national community-based prospective register of first-ever strokes, using multiple overlapping sources of notification, was established. Results-During the first year, 352 patients (95.2% black) were registered, 142 males and 210 females (59.7%), with a mean age of 72.5 years (range 24 to 104; SD 14.8). Cerebral infarction (IS) occurred in 81.8%, intracerebral hemorrhage (ICH) in 11.9%, subarachnoid hemorrhage (SAH) in 2.0%, whereas 4.3% of strokes were unclassified (UC). The crude annual incidence rate for the black population was 1.40 (95% CI: 1.25,1.55) per 1000 (1.35 standardized to the European population) for all strokes, 1.20 (1.07,1.34) for IS, 0.18 (0.12,0.23) for ICH, and 0.03 (0.01,0.05) for SAH. Lacunar infarction (LACI) accounted for 50.7% of IS among the black population, whereas 15.6% and 26.8% were caused by total anterior circulation infarction (TACI) and partial anterior circulation infarction (PACI), respectively. At 7 and 28 days, respectively, case fatality rates for blacks were 13.1% and 27.8% for all strokes, 46.3% and 58.5% for ICH, 7.6% and 21.7% for IS, 32.6% and 65.1% for TACI, and 2.1% and 9.0% for LACI. Conclusions-Stroke incidence among the black population of Barbados is lower than among African-origin populations in the USA and UK. Lacunar infarction is the predominant stroke subtype.