Hypertension in Sub-Saharan Africa: Cross-Sectional Surveys in Four Rural and Urban Communities

Marleen E Hendriks,Jacques Van Der Gaag,Peter Gatongi,Ingrid H De Beer,Marijke T L Roos,Igna Bonfrer,Constance Schultsz,Berber Kramer,Tanimola M Akande,Joep M A Lange,Amos M Kahwa,Gert Van Rooy,Sayoki G Mfinanga,Wendy Janssens,Esegiel Gaeb,Ferdinand W N M Wit,Tobias F Rinke De Wit,Lizzy M Brewster,Judith Lammers

doi:10.1371/journal.pone.0032638

Abstract

BackgroundCardiovascular disease (CVD) is the leading cause of adult mortality in low-income countries but data on the prevalence of cardiovascular risk factors such as hypertension are scarce, especially in sub-Saharan Africa (SSA). This study aims to assess the prevalence of hypertension and determinants of blood pressure in four SSA populations in rural Nigeria and Kenya, and urban Namibia and Tanzania.Methods and FindingsWe performed four cross-sectional household surveys in Kwara State, Nigeria; Nandi district, Kenya; Dar es Salaam, Tanzania and Greater Windhoek, Namibia, between 2009–2011. Representative population-based samples were drawn in Nigeria and Namibia. The Kenya and Tanzania study populations consisted of specific target groups. Within a final sample size of 5,500 households, 9,857 non-pregnant adults were eligible for analysis on hypertension. Of those, 7,568 respondents ≥18 years were included. The primary outcome measure was the prevalence of hypertension in each of the populations under study.The age-standardized prevalence of hypertension was 19.3% (95%CI:17.3–21.3) in rural Nigeria, 21.4% (19.8–23.0) in rural Kenya, 23.7% (21.3–26.2) in urban Tanzania, and 38.0% (35.9–40.1) in urban Namibia. In individuals with hypertension, the proportion of grade 2 (≥160/100 mmHg) or grade 3 hypertension (≥180/110 mmHg) ranged from 29.2% (Namibia) to 43.3% (Nigeria). Control of hypertension ranged from 2.6% in Kenya to 17.8% in Namibia. Obesity prevalence (BMI ≥30) ranged from 6.1% (Nigeria) to 17.4% (Tanzania) and together with age and gender, BMI independently predicted blood pressure level in all study populations. Diabetes prevalence ranged from 2.1% (Namibia) to 3.7% (Tanzania).ConclusionHypertension was the most frequently observed risk factor for CVD in both urban and rural communities in SSA and will contribute to the growing burden of CVD in SSA. Low levels of control of hypertension are alarming. Strengthening of health care systems in SSA to contain the emerging epidemic of CVD is urgently needed.

Highlights

Eighty percent of global cardiovascular disease (CVD) mortality occurs in low- and middle-income countries (LMIC) [1,2]
This study describes the prevalence of hypertension and the determinants of increasing blood pressure in 4 sub-Saharan Africa (SSA) populations in rural Nigeria and Kenya and in urban Namibia and Tanzania
The mean age distribution of the populations ranged from 36.8 years in Tanzania to 45.3 in Nigeria

Summary

Introduction

Eighty percent of global cardiovascular disease (CVD) mortality occurs in low- and middle-income countries (LMIC) [1,2]. Migration studies in LMIC showed that migrants from rural to urban areas showed an increase in blood pressure [14,15]. Hypertension prevalence data are crucial for understanding the magnitude of the problem, identifying groups at high risk for CVD, and evaluating the effects of policy and practice interventions [20]. This study describes the prevalence of hypertension and the determinants of increasing blood pressure in 4 SSA populations in rural Nigeria and Kenya and in urban Namibia and Tanzania. Cardiovascular disease (CVD) is the leading cause of adult mortality in low-income countries but data on the prevalence of cardiovascular risk factors such as hypertension are scarce, especially in sub-Saharan Africa (SSA). This study aims to assess the prevalence of hypertension and determinants of blood pressure in four SSA populations in rural Nigeria and Kenya, and urban Namibia and Tanzania

Objectives

Methods

Results

Discussion

Conclusion