Epidemic Hypertension in Nigerian Workers

BACKGROUND:

This dynamic population provided a valuable opportunity to gain important information about the etiology of hypertension which would be much more difficult to gain from a United States Black population because higher weight and blood pressure are already entrenched and static in the United States population.

DESIGN NARRATIVE:

From 1991 to 1996, a cross-sectional study was conducted to test the hypothesis that differences in hypertension prevalence were primarily related to differences in SES. The higher prevalence of hypertension among the high SES Nigerian professionals was thought to be related to higher weight, caloric intake, Westernization of diet, alcohol intake, sodium intake, cardiovascular reactivity, and stress due to job, migration, and change in SES, and to reduced potassium intake and physical activity. Civil servants were systematically sampled from civil service employee lists. Data were collected on blood pressure; urinary sodium, potassium, and protein; diet; anthropometry; electrocardiogram; serum insulin; stress in the work environment, migration history, and cardiovascular reactivity.

In FY 1992, the Office of Research on Women's Health provided supplemental funds to enlarge the study and to perform gender analyses. The supplemental funds were used to determine whether fatty acid distributions, and their relationships to cardiovascular risk factors differed between Nigerian women and United States Black women; United States Black women and United States white women; and Nigerian women and Nigerian men. Forty men and forty women, ages 18 to 30, were chosen randomly from the Nigerian civil servant population. Subjects with hypertension, those using oral contraceptives, or any medication affecting the sympathetic nervous system, were excluded. The Nigerian subjects were compared with 40 Black and 40 white healthy female volunteers at the University of Pittsburgh.

The grant was renewed in 1996 through August 2001 to conduct a longitudinal study of 726 members of the original cohort. The purpose was to determine the importance of weight gain and weight-related factors, and the possible interaction of other factors, e.g. psychosocial, electrolytes, reactivity, macronutrient intake, to change in blood pressure. Factors related to weight gain were identified. The high prevalence of the electrocardiogram left ventricular hypertrophy (ECG-LVH) was validated against echocardiographic measures (ECHO-LVH). Predictors of change in ECG-LVH, and the correlates of microalbuminuria were identified. In Year 2 (Cohort Year 4) half of the population was restudied with echocardiography, cardiovascular reactivity, and new psychosocial measures. In Year 4 (Cohort Year 6), with the exception of cardiovascular reactivity, the full cohort was re-examined for baseline measures, including multiple blood pressure readings, height, weight, waist, hips, ECG, physical activity, two 24 hour dietary recalls, alcohol intake, menopausal status, psychosocial measures, 24 hour urine for sodium, potassium, creatinine, micro-albuminuria, and fasting serum for lipids, insulin, glucose, and creatinine.

The study completion date listed in this record was obtained from the "End Date" entered in the Protocol Registration and Results System (PRS) record.