Pulse Pressure Relationships with Demographics and Kidney Function in Ashanti, Ghana.

INTRODUCTION: Hypertension, particularly pulse pressure [PP] is a major risk factor for end-stage renal disease. However, the effect of individual components of hypertension namely PP, systolic [SBP] and diastolic blood pressure [DBP] on kidney function, in the general African population is unknown. METHODS: Data were collected on 944 participants [aged 40-75 y], living in villages in the area around the city of Kumasi, Ghana, on demographics, medications, height, weight, BP and 24-hour creatinine clearance (CrCl). RESULTS: The demographic and clinical characteristics were: age 55(11) [mean (SD)] years, females 62%, rural village-dwellers 52%, diabetes 1·5%, BMI 21(4) kg/m2, 24-hourCrCl as a measure of glomerular filtration rate (GFR) 84(23) ml/min/1.73 m2. 29% had BP >140/90 mmHg; SBP and DBP were 125/74(26/14) mmHg, PP was 51(17) mmHg. PP increased with age by 0.55(95% CI: 0.46,0.64) mmHg/year. PP was higher (53(17) v 49(15) mmHg; p < 0.001) in the semiurban participants. GFR decreased both with increasing PP [-0.19 (-0.27,-0.10 ml/min/1.73 m2/mmHg; p < 0.001] and SBP [-0.09 (-0.14,-0.03) ml/min/1.73 m2/mmHg; p < 0.001] but there was no significant relationship with DBP [-0.04 (-0.15,0.06)]. After adjusting for SBP, the relationship between GFR and PP became steeper [-0.31 (-0.50,-0.12) ml/min/1.73 m2/mmHg; p < 0.001]. Using multivariate regression analysis that included PP, age, gender, BMI, only increasing age [-0.75 (-0.88,-0.62)] and decreasing BMI [0.49 (0.16,0.81)] were associated with decreased kidney function. CONCLUSIONS: In this homogeneous West-African population, PP increased with age and had a steeper relationship with declining kidney function than SBP or DBP.

Blood Pressure and Haematological Indices in Twelve Communities in Ashanti, Ghana.

Hypertension is the most important risk factor for cardiovascular mortality and morbidity in Sub-Saharan Africa. In western populations, high haemoglobin levels are associated with raised BP unlike in Sub-Saharan Africa where there is a paucity of data. Our study examines the association between haematological indices with BP variables. Weight, height, BP, and whole blood indices of viscosity (Hb, haematocrit, RBC count, and MCV) were measured in 921 adults (340 men, 581 women; aged 40-75) in 12 communities in Ghana. Mean values for Hb (12.3 g/dl ± 1.7 SD), haematocrit (36.7% ± 5.2), RBC (4.10 million/µL ± 0.64), and MCV were lower than reference values used in Sub-Saharan Africa. Mean BMI was 21.1 ± 4.1 indicating a lean population. Systolic BP increased by 1.0 mmHg (95% CI 0.5-1.5), p < 0.001, for women and 0.5 (0.1-1.0), p = 0.027, for men per unit increase in haematocrit. Similar relationships were found for Hb and RBC but not for MCV or platelets. The relationships were weaker when adjusted for BMI, 0.7 mmHg (0.2-1.2) in women and 0.5 (0.0-1.0) in men. Findings for diastolic BP were similar. Overall haematological indices were low. We have found a significant, positive relationship between BP, Hb, Haematocrit, and RBC count in our population.

Assessment of GFR by four methods in adults in Ashanti, Ghana: the need for an eGFR equation for lean African populations.

BACKGROUND: Equations for estimating glomerular filtration rate (GFR) have not been validated in Sub-Saharan African populations, and data on GFR are few. METHODS: GFR by creatinine clearance (Ccr) using 24-hour urine collections and estimated GFR (eGFR) using the four-variable Modification of Diet in Renal Disease (MDRD-4)[creatinine calibrated to isotope dilution mass spectrometry (IDMS) standard], Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) and Cockcroft-Gault equations were obtained in Ghanaians aged 40-75. The population comprised 1013 inhabitants in 12 villages; 944 provided a serum creatinine and two 24-hour urines. The mean weight was 54.4 kg; mean body mass index was 21.1 kg/m(2). RESULTS: Mean GFR by Ccr was 84.1 ml/min/1.73 m(2); 86.8% of participants had a GFR of >/=60 ml/min/1.73 m(2). Mean MDRD-4 eGFR was 102.3 ml/min/1.73 m(2) (difference vs. Ccr, 18.2: 95% CI: 16.8-19.5); when the factor for black race was omitted, the value (mean 84.6 ml/min/1.73 m(2)) was close to Ccr. Mean CKD-EPI eGFR was 103.1 ml/min/1.73 m(2), and 89.4 ml/min/1.73 m(2) when the factor for race was omitted. The Cockcroft-Gault equation underestimated GFR compared with Ccr by 9.4 ml/min/1.73 m(2) (CI: 8.3-10.6); particularly in older age groups. GFR by Ccr, and eGFR by MDRD-4, CKD-EPI and Cockcroft-Gault showed falls with age: MDRD-4 5.5, Ccr 7.7, CKD-EPI 8.8 and Cockcroft-Gault 11.0 ml/min/1.73 m(2)/10 years. The percentage of individuals identified with CKD stages 3-5 depended on the method used: MDRD-4 1.6% (7.2 % without factor for black race; CKD-EPI 1.7% (4.7% without factor for black race), Ccr 13.2% and Cockcroft-Gault 21.0%. CONCLUSIONS: Mean eGFR by both MDRD-4 and CKD-EPI was considerably higher than GFR by Ccr and Cockcroft-Gault, a difference that may be attributable to leanness. MDRD-4 appeared to underestimate the fall in GFR with age compared with the three other measurements; the fall with CKD-EPI without the adjustment for race was the closest to that of Ccr. An equation tailored specifically to the needs of the lean populations of Africa is urgently needed. For the present, the CKD-EPI equation without the adjustment for black race appears to be the most useful.

A community programme to reduce salt intake and blood pressure in Ghana [ISRCTN88789643].

BACKGROUND: In Africa hypertension is common and stroke is increasing. Detection, treatment and control of high blood pressure (BP) is limited. BP can be lowered by reducing salt intake. In Africa salt is added to the food by the consumer, as processed food is rare. A population-wide approach with programmes based on health education and promotion is thus possible. METHODS: We carried out a community-based cluster randomised trial of health promotion in 1,013 participants from 12 villages (628 women, 481 rural dwellers); mean age 55 years to reduce salt intake and BP. Average BP was 125/74 mmHg and urinary sodium (UNa) 101 mmol/day. A health promotion intervention was provided over 6 months to all villages. Assessments were made at 3 and 6 months. Primary end-points were urinary sodium excretion and BP levels. RESULTS: There was a significant positive relationship between salt intake and both systolic (2.17 mmHg [95% CI 0.44 to 3.91] per 50 mmol of UNa per day, p < 0.001) and diastolic BP (1.10 mmHg [0.08 to 1.94], p < 0.001) at baseline. At six months the intervention group showed a reduction in systolic (2.54 mmHg [-1.45 to 6.54]) and diastolic (3.95 mmHg [0.78 to 7.11], p = 0.015) BP when compared to control. There was no significant change in UNa. Smaller villages showed greater reductions in UNa than larger villages (p = 0.042). Irrespective of randomisation, there was a consistent and significant relationship between change in UNa and change in systolic BP, when adjusted for confounders. A difference in 24-hour UNa of 50 mmol was associated with a lower systolic BP of 2.12 mmHg (1.03 to 3.21) at 3 months and 1.34 mmHg (0.08 to 2.60) at 6 months (both p < 0.001). CONCLUSION: In West Africa the lower the salt intake, the lower the BP. It would appear that a reduction in the average salt intake in the whole community may lead to a small but significant reduction in population systolic BP.

Blood pressure and body mass index in lean rural and semi-urban subjects in West Africa.

BACKGROUND: Blood pressure (BP) is positively related to body mass index (BMI) in persons of both Caucasian and African origin, but the precise nature of the relationship is unclear. OBJECTIVE: To study the relationship between BP and BMI in a lean African population. DESIGN: A community-based cross-sectional study. METHODS: The BMI and BP were measured in 362 men and 592 women aged 40-75 years living in Ashanti, Ghana. In total, 498 lived in semi-urban areas and 456 in rural villages. RESULTS: The BMI was higher among semi-urban women [23.1 kg/m (95% confidence interval (CI), 22.5 to 23.6)] than semi-urban men [20.9 kg/m (95% CI, 20.6 to 21.5)], rural men [19.5 kg/m (95% CI, 19.1 to 19.9)] and rural women [19.9 kg/m (95% CI, 19.5 to 20.3)]. For systolic BP in women older than 52 years and in semi-urban women, the relationship was non-linear. The slope of the line below the change point ("knot") was greater than that above it. There was no evidence of non-linearity in men. For diastolic BP only younger women had a significant "knot" point at 18 kg/m. Again, the slope of the line below the "knot" was greater than that above it. In men, however, there was also evidence of a "knot" in younger and rural men, with the slope of the line below the "knot" being less that that above it (unlike in women). CONCLUSIONS: The relationship between BP and BMI is not linear, and is possibly sigmoid, but this may vary between subgroups.

Rural and semi-urban differences in salt intake, and its dietary sources, in Ashanti, West Africa.

OBJECTIVES: To provide a socioeconomic profile of rural and semi-urban settings in Ashanti, West Africa and to investigate the relationship between urbanization and sources of salt in the diet. SETTING: 12 villages (6 rural, 6 semi-urban) participating in a cluster randomized controlled trial of a health promotion in the Ashanti region of Ghana. PARTICIPANTS: 1013 adult men (N = 385) and women (N = 628), aged 40-75. METHOD: Between June 2001 and June 2002, participants completed a detailed questionnaire on demography, occupation and education, housing, radio and television use, personal and family medical history, drug therapy, smoking, alcohol consumption, and diet. RESULTS: 532 subjects lived in semi-urban and 481 in rural communities. Ninety-two percent of the participants were of the Ashanti tribe and 94% spoke Twi. The semi-urban villages were closer to Kumasi, the second largest city in Ghana, had larger population (1727 vs 1100 people) and household sizes (14.6 vs 8.8 persons per household; P < .001), had fewer farmers (53% vs 81%; P < .001) and more traders (22% vs 7%; P < .001), and had more homes with electricity (81% vs 17%; P < .001) and piped water (28% vs 0.2%; P < .05). Semi-urban villagers had higher systolic blood pressure than rural villagers (129 vs 121 mm Hg difference 8 mm Hg [95% CI 5-11]; P < .001). Salt is almost invariably added to food in cooking (98%), and salted foods such as fish and meat are eaten in both communities. Salt is often added at the table (52%), more often in rural villages than in semi-urban settings (59% vs 45%; P < .01), although the total salt consumed as measured by urinary sodium was similar (99 vs 103 mmol/day). Potassium levels were higher in rural villages (58 vs 40 mmol/day difference 18 mmol/day [95% CI 11-26]; P < .001). CONCLUSIONS: In this mainly farming community were clear differences in housing, population structure, and blood pressure between rural and semi-urban communities. While no significant differences were in the amount of salt consumed, the sources of salt differed between rural and semi-urban settings. Finally, rural villagers ate more potassium than semi-urban participants.

Prevalence, detection, management, and control of hypertension in Ashanti, West Africa.

Hypertension and stroke are important threats to the health of adults in sub-Saharan Africa. Nevertheless, detection of hypertension is haphazard and stroke prevention targets are currently unattainable. Prevalence, detection, management, and control of hypertension were assessed in 1013 men (n=385) and women (n=628), both aged 55 [SD 11] years, living in 12 villages in Ashanti, Ghana. Five hundred thirty two lived in semi-urban and 481 in rural villages. The participants underwent measurements of height, weight, and blood pressure (BP) and answered a detailed questionnaire. Hypertension was defined as BP > or =140 and/or > or =90 mm Hg or being on drug therapy. Women were heavier than men. Participants in semi-urban areas were heavier and had higher BP (129/76 [26/14] versus 121/72 [25/13] mm Hg; P<0.001 for both) than in rural areas. Prevalence of hypertension was 28.7% overall and comparable in men and women, but higher in semi-urban villages (32.9% [95% CI 28.9 to 37.1] versus 24.1% [20.4 to 28.2]), and increased with age. Detection rate was lower in men than women (13.9% versus 27.3%; P=0.007). Treatment and control rates were low in both groups (7.8% and 4.4% versus 13.6% and 1.7%). Detection, treatment, and control rates were higher in semi-urban (25.7%, 14.3%, and 3.4%) than in rural villages (16.4%, 6.9%, and 1.7%). Hypertension is common in adults in central Ghana, particularly in urban areas. Detection rates are suboptimal in both men and women, especially in rural areas. Adequate treatment of high BP is at a very low level. There is an urgent need for preventive strategies on hypertension control in Ghana.