| Abstract
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The determinants of hypertension (HT) in West Africa have not been well defined. In this study we sampled 598 men and women, 45 years of age and older, from a recently completed population-based survey in southwest Nigeria; 190 men and women from a rural area, 205 men and women from among the urban poor, and 203 men who were retired railway workers. Extensive training of local field staff was completed and measurements at all sites were made by a single team. The mean age of the sample was usd61\pm10usd and mean blood pressures were low relative to westernized societies (SBP = usd124 \pm 24usd, DBP = usd72 \pm 13usd mmHg). Men and women were lean (BMI = usd21.3\pm3.6usd and usd23.0\pm5.2usd kg/m2, respectively). Prevalence of HT increased across the gradient from rural farmers to urban poor to railway workers: 14%, 24%, 29%, and 3%, 11%, 14%, based on the 140/90 and 160/95 cut-points, respectively (p < 0.01). Urinary electrolyte excretion was usd110\pm57usd mEq/24H for sodium and usd46\pm24usd/24H for potassium, with mean sodium:potassium ratio of usd2.6\pm1.0usd. The ratio was higher among the urban residents (p < 0.01), primarily a result of lower potassium intake, and was correlated with SBP and DBP (r = 0.16 and 0.18, respectively, p usd Women demonstrated protective effects of social integration (SI) on HT (OR = 0.34, 95% CI = 0.17, 0.69), and an inverse correlation between SI and SBP (r = 0.25, 95% CI = usd-0.37,-0.12usd). For men, the relationship between SI and BP was modified by socio-economic site. When stratified by occupation class, SI was positively correlated with SBP for those in farming and wage work, (r = 0.20, 95% CI = 0.02, 0.40 and r = 0.13, 95% CI = 0.06, 0.31, respectively). For men and women engaged in trade and craft work, however, the inverse association persisted (r = 0.18, 95% CI = usd-0.29,-0.06usd). These findings provide quantitative estimates of the impact of the known risk factors for hypertension in West Africa and demonstrate the basis for the increase in hypertension with urbanization and associated economic and dietary change. The prevalence of risk factors and of hypertension are modest even among the elderly in this population, in marked contrast to findings among persons of African descent in industrialized countries. These data provide support for recommendations for the prevention of hypertension in West African society and provide a benchmark against which to compare populations in the African diaspora.
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