Hypertension in a black population: prevalence and biosocial determinants of high blood pressure in a group of urban Nigerians

Abstract

Aims: To define the prevalence of hypertension, a major cause of morbidity and mortality in blacks, and related biosocial factors in an urban African population group.

Methods: The setting was that of a civil service population in Ibadan, a major city in Southwestern Nigeria. Nine hundred and ninety-eight civil servants selected by multistage sampling participated in the survey. Biosocial data including smoking history, alcohol use and level of physical activity; anthropometry, blood pressure and plasma glucose measurements were obtained. Diagnosis of hypertension was based on blood pressure of ⩾160/95 mm Hg or known hypertensive on treatment.

Results: The overall prevalence rate of hypertension was 10.3% (CI, 8.4%, 12.2%), rates of 13.9% and 5.3% were obtained in men and women respectively in spite of a much higher rate of generalised obesity in the latter. Hypertension was associated with higher salary grade level, but there was no relationship found with regular exercise, smoking and alcohol. Obesity (body mass index (BMI) ⩾30 kg/m²) was associated with hypertension only in women. A two-sided t-test demonstrated age, waist circumference, waist to hip ratio (WHR) and plasma glucose level as significant variables. In multivariate ANOVA models of systolic blood pressures, age, male sex and BMI were highly significant factors (P < 0.0001) and plasma glucose was also significant (P < 0.016); the same variables (except plasma glucose) were associated with diastolic blood pressures. in logistic regression models the variables which predicted hypertension were whr, plasma glucose, age, sex and family history of diabetes.

Conclusions: Prevalence of hypertension in the study was comparable to recently reported rates in urban Nigeria and similar populations in Africa. The biosocial determinants of hypertension in the urban black population were age, male gender, higher socio-economic status, BMI, plasma glucose, generalised and central adiposity. Regional fat distribution was a stronger predictor of hypertension than generalised obesity in the population.