Introduction: Systemic hypertension is a rapidly growing epidemic in Sub-Saharan Africa. Adequacy of blood pressure(BP) control and the factors influencing it, especially the role of socio-economic status(SES) have not been well studied in this part of the world.
Hypothesis: We therefore aimed to quantify the association of SES both at the individual and at the country level with BP control in Sub-Saharan Africa.
Methods: We conducted a cross-sectional survey in urban clinics of twelve countries, both low-income and middle-income, in Sub-Saharan Africa. Data were collected on demographics, treatment and standardized BP measures were made among the hypertensive patients attending the clinics. BP control was defined as BP<140/90 mmHg and hypertension grades were defined according to European Society of Cardiology guidelines. Country income was retrieved from the World Bank database and patient’s individual wealth status was documented by the treating physician. The separate association between SES (both country-level income and individual patient wealth) and BP control was investigated using Generalized Linear Mixed-Effects Models adjusted on sex and age.
Results: A total of 2198 hypertensive patients (58.4±11.8years; 39.9% male) were included, of whom 1017(46.3%) were from low-income and 1181(53.7%) from middle-income countries. Individual wealth level was low, mid and high in 376(17.6%), 1053(49.2%) and 713(33.3%) patients respectively. Uncontrolled hypertension was present in 1692 patients(77.4%) including 1044(47.7%) with ≥grade 2 hypertension. The proportion of uncontrolled hypertension progressively increased with decreasing level of patient individual wealth, respectively 72.8%, 79.3% and 81.8%(p for trend<0.01). Stratified analysis shows that these differences of uncontrolled hypertension according to individual wealth index were observed in low-income countries(p for trend=0.03) and not in middle-income countries(p for trend=0.26). In low-income countries the odds of uncontrolled hypertension increased 1.37 fold(OR=1.37 [0.99-1.90]) and 1.88 fold(OR=1.88 [1.10-3.21]) in patients with middle and low individual wealth as compared to high individual wealth. Similarly, the grade of hypertension increased progressively with decreasing level of individual patient wealth(p for trend <0.01).
Conclusions: Low individual wealth was significantly associated with poor hypertension control, especially in low-income countries. Strategies for hypertension control in Sub-Saharan Africa should especially focus on people in the lowest individual wealth groups who also reside in low-income countries.