High Blood Pressure in Sub-Saharan Africa: The Urgent Imperative for Prevention and Control.

Abstract

Higher-than-optimal blood pressure (BP), along with tobacco use and dyslipidemia, is one of the three most important modifiable risk factors for CVD. For more than 2 decades, studies have indicated an escalating pattern of hypertension in SSA.1, 2 Estimates indicate unacceptably high rates of undiagnosed and poorly controlled disease in SSA, in spite of substantially enhanced knowledge on pharmacologic and lifestyle interventions for controlling BP. The reasons for the escalating burden of hypertension in SSA are yet fully elucidated; however, important drivers include rapid urbanization, adoption of unhealthy eating habits, and sedentary lifestyles. Addressing hypertension in SSA requires multipronged interventions to achieve better prevention, detection, and control of the condition. In this article, we discuss the urgency of prevention as a priority for hypertension control, as well as possible strategies to be employed to initiate health service and community-based actions toward the prevention of hypertension in SSA. High BP is one of the leading causes of death and disability globally,1, 2 and significantly affects countries within SSA. Between 1990 and 2010, the prevalence of hypertension in SSA increased by 67%, and hypertension was responsible for more than 500,000 deaths and 10 million years of life lost in 2010 in the region.2 This is at variance with many other countries worldwide where absolute BP levels and prevalence of hypertension may be decreasing.2 The prevalence of hypertension in some SSA countries are among the world's highest. A recent review showed that hypertension prevalence varies between 15% and 70%, with an average of 30%, among SSA countries.3 Furthermore, between 44% and 93% of people with hypertension in SSA are unaware of their hypertensive status.3 The extent of the adverse effects of hypertension on the health and lives of populations within SSA remains largely unexplored. Extrapolations from studies among African descents in the diaspora suggest that the outcomes of hypertension among populations in SSA are likely devastating. Indeed, the few studies conducted among SSA populations indicate that up to 42% of cases of ischemic heart disease (IHD) are related to hypertension,4 that hypertension increases the risk of stroke by at least five-fold,5 and that a third of heart failure cases in SSA are caused by hypertension.6 Other potential consequences of elevated BP in SSA that are becoming increasingly common are chronic kidney disease,7 adverse pregnancy outcomes,8 and vascular dementia.9 The likelihood of these poor outcomes is heightened by the low uptake of treatments for hypertension in SSA. Only about 18% of individuals with hypertension in SSA receive any treatment for hypertension, with only about 7% achieving target BP control levels.3 Treating hypertension is expensive, imposing a huge economic burden on individuals and national healthcare systems in SSA, mainly because of the costs associated with controlling BP and the treatment of complications. This has a major impact on healthcare spending,10 with an estimated 7.3% of total healthcare spending directly related to higher-than-optimal BP and its complications in SSA. In 2001, more than US $2 billion was spent on hypertension-related diseases.10 The cost estimates would probably be higher if disease-related medical costs for the extremely high proportion of people with undiagnosed hypertension were recognized and accounted for. Furthermore, indirect costs from lost productivity caused by disability and premature mortality are important considerations, as hypertension and related complications disproportionately affect the economically productive age groups in SSA. Historical reports indicate that hypertension has been essentially nonexistent in some rural communities in SSA,11 which contrast with the surge in morbidity and mortality observed in more recent years. This increase is likely part of the epidemiologic transition accompanying socioeconomic changes that occur across Africa, with several environmental factors playing a role, in populations that possibly carry permissive genetic factors.12 The main environmental factors are unhealthy dietary pattern (including high saturated fat, high sodium, and low potassium intake and alcohol abuse), physical inactivity, and high stress level.12 This is in line with observations from economically developed countries, where increased salt consumption, low dietary potassium, obesity, and physical inactivity play an important role in the occurrence of hypertension. The contribution of dietary salt intake may be particularly important in SSA, as some studies suggest that black populations are more salt sensitive than other ethnic groups.13, 14 Although more investigations are needed, the contribution of lifestyle factors to the epidemic of hypertension in SSA is increasingly being clarified.15 Indeed, it is known that at least 27.5% of the population in Africa is physically inactive;16 more than 30% of adults are overweight or obese;17 and alcohol consumption adversely influences the BP levels of African populations.18 Although studies on sodium and potassium content of local foods are scarce in SSA, the few available findings have suggested the potentially important role of these factors in SSA.19-22 Owing to nutrition transitions driven by industrialization and globalization, consumption of high sodium foods is increasing across SSA, and the spread of ready-made meals within global supermarket chains and fast-food restaurants is reinforcing these trends. In addition to the aforementioned factors, tobacco use, which is fast increasing in SSA,23 is especially important in people with hypertension, increasing the overall cardiovascular risk. On the other hand, certain environmental factors that are more specific to SSA, such as perinatal malnutrition (and “early programming”), may play an additional role.12 Potential genetically determined factors such as low renin level and high sodium absorption rates have been shown to be higher among black individuals, which may potentiate the environmental risk factors described above. More longitudinal studies of the frequency and risk factors of hypertension are needed in SSA to understand trends and clarify the relative contributions of the various environmental and genetic factors (as well as the gene-environment interaction). Areas still unexplored include factors such as stress that may be becoming much more of a problem with urbanization in SSA.24 Consideration of prevention of hypertension as an urgent policy priority in SSA rests on two main premises: (1) the prohibitively high costs of managing hypertension and related complications in the context of limited resources and competing national priorities that may relegate care for hypertension to second-tier concerns, and (2) the unique demographic variations in distribution of the disease that tend to affect younger people in SSA. The preventive efforts should be multifaceted, including primary and secondary prevention strategies, with a particular focus on high-risk individuals for the secondary prevention effort. Investments in prevention can be cost-effective and some interventions are estimated to be cost-saving.25 Population-wide interventions aimed at improving diet (eg, reduction of added salt through food reformulation and raising awareness public awareness) and physical activity can be cost-effective and several interventions are estimated to be cost-saving and/or generate revenues (eg, taxes on alcohol, tobacco, and sugar) and help people in making healthy lifestyle choices. The private sector and food industry also have an important role in ensuring that healthy foods are available and affordable, and that food is adequately labeled and/or otherwise identified as healthy in a way that is understandable for most consumers. Recommended polices to prevent or manage hypertension through improved diet and physical activity are outlined in the World Health Organization (WHO) Global Action Plan 2013 to 2020 to Prevent and Control Noncommunicable Diseases (NCDs) and in the WHO 2014 Global Status Report on NCDs. WHO member states have agreed on nine targets to be achieved by 2025, using the year 2010 as the baseline. These targets, which are relevant for hypertension prevention and control, include: (1) a 25% reduction in NCDs; (2) a 10% reduction in alcohol use; (3) a 10% reduction in prevalence of insufficient physical activity; (4) a 30% reduction in mean population salt intake; (5) a 30% reduction in the prevalence of tobacco use; (6) a 25% reduction in the prevalence of raised BP; (7) a 0% increase in obesity and diabetes; (8) at least a 50% rate of eligible people receiving drug therapy and counseling to prevent heart attack and stroke; and (9) an 80% availability of the affordable technologies and essential medicines, including generics, required to treat major NCDs at both public and private facilities. The future benefits to both healthcare budgets and to society from primary prevention of hypertension are clear, but the immediate cost of financing hypertension prevention programs can be an obstacle in poorer countries. The low gross domestic product for SSA countries suggests that these countries cannot afford to underwrite the costs of even a limited national hypertension prevention program. A focus on primary prevention (which is less costly than secondary prevention) and securing contributions from novel funding sources, namely national, international, supranational, and philanthropic agencies, will be essential for a successful hypertension prevention strategy in SSA countries. SSA has one of the lowest rates of awareness, treatment, and control of hypertension around the world. To effectively reduce the burden of hypertension, a focus on the identification of people at high risk has relevance. Secondary prevention of hypertension could be more efficiently achieved as part of a broader global cardiovascular risk reduction, as most people with hypertension also have additional cardiovascular risk factors and/or evidence of end-organ injury (heart disease, stroke, kidney disease) that contribute to overall cardiovascular risk. Such an approach to management of a person's global cardiovascular risk should be encouraged in SSA, as incorporating hypertension treatment in a multicomponent chronic disease management package is likely to be effective in terms of maximizing health benefits and minimizing costs. Furthermore, lowering of BP while accounting for the overall cardiovascular risk is likely to be much more effective.26 Although hypertension prevention strategies can possibly be modeled after those used in Western countries, a better approach to hypertension control in SSA requires an understanding of potential barriers and enablers to translation at the individual, societal, and health system levels. There are several critical gaps to be addressed in the efforts to prevent and control hypertension and NCDs at large in SSA. Good news perhaps is that increasing awareness of NCDs among policy makers has led to a gradual establishment in almost all SSA countries of national programs and structures to prepare and coordinate countries responses to NCDs including hypertension.27 However, the good news often ends there in the sense that existing NCDs structures/programs are generally not all-encompassing, in that they do not always include societal/environmental perspectives, they are underfunded, and they are not always operational.28 Of the 38 SSA countries respondent to the WHO's NCD Country Capacity Survey (CCS), only 14 (37%) declared having an operational national policy, strategy, or action plan to reduce unhealthy diets and/or promote healthy diet.28 With reference to hypertension specifically, South Africa is the only country in the region with a national program to reduce dietary salt intake, while most other countries are lacking reliable data on salt consumption levels. Globally, the processed food industry has an important role in adversely affecting cardiovascular risk through widespread social marketing and distribution of food rich in salt, refined sugar, and saturated and trans fats, and low in fiber, complex carbohydrates, potassium, and calcium. Comprehensive policies to limit the impact of deliberate and intentional marketing of unhealthy foods, alcohol, and tobacco should therefore be a priority to help prevent NCDs. In most of Africa, there is a limited capacity of the healthcare system to provide adequate prevention and control for NCDs and related risk factors. A case in point is a study in Tanzania that showed inadequacy in guidelines, diagnostic equipment, and first-line drug therapy for the primary care of hypertension, as well as weak management, training, and reporting systems.29 Investments are necessary to ensure that an adequately trained workforce is available, and that communities and healthcare facilities have adequate equipment (eg, BP devices) and screening programs, including the capacity to treat detected hypertension cases. Most patients in SSA settings have to pay for medical care and medication out-of-pocket, which can constitute a major barrier to healthcare services and adherence to long-term or lifelong treatment. It is therefore essential to set up effective procurement systems for low-cost BP-lowering medications. Furthermore, given the shortage of trained physicians in SSA, shifting tasks to trained nurses may represent a viable alternative to achieve better hypertension prevention and control.30, 31 Other barriers include social circumstances related to beliefs and influence by peers,32 motivational, and financial, some of which can be reasonably addressed through policy-level interventions to increase access to insurance such as affordability of services.33 The potential benefits of prevention and control of hypertension to both healthcare budgets and to society are clear, but the immediate cost of financing hypertension prevention and control programs can be prohibitive in poorer SSA countries. Contributions from novel funding sources, namely international, supranational, and philanthropic agencies, can play an important role in the successful implementation of hypertension programs in many SSA countries. Such alliances can be modelled after HIV/AIDS preventions programs in SSA, which have been very successful. Laudable initiatives, championed by governments and foundations, have transformed lives and restored hope to millions of people with HIV infection and AIDS in SSA. A similar concerted international effort targeting hypertension prevention is needed now—before the looming epidemic takes a much stronger hold. This would require a number of measures that include a realignment of funding with the emerging NCDs in SSA, support to civil societies and health-related organizations, development of strategies and advocating for actions to prevent and control NCDs, and provision of funding for forums to share best practices for prevention and control of NCDs and to bring and update best practices to healthcare workers in SSA. A more futuristic approach may include going beyond internationally funded public health initiatives and thinking about innovative mechanisms to fund the establishment of viable and appropriately tailored (to local specificities) primary care networks within countries, which are mostly weak at this point.34 Indeed, the Cuban experience of a relatively successful approach to controlling and increasing awareness of hypertension than in other low- to middle-income countries,35 within the framework of a well-organized and efficient primary care system,36 indicates that improvement or establishment of viable primary care networks in SSA countries in addition to existing public health initiatives is key to ensuring long-term success. Hypertension prevention policies in SSA need to be multifaceted and require coordinated efforts within the healthcare establishment and the wider society to achieve their goals within the framework of reducing NCDs in line with the current global agenda. Special attention should be given to the promotion of physical activity, healthy nutrition including reduction in dietary salt intake, and healthy living and working environments. Legislative action is needed to mandate food labeling and foster a culture of health promotion, with mass media used to disseminate information regarding hypertension and prevention. In addition, hypertension prevention strategies need to be funded from specific budgetary allocations, and clear targets and quality indicators should be established. Strengthening of healthcare systems to increase their capacity is necessary to better address primary and secondary prevention of hypertension and other NCDs. This would include reliance on and training of large numbers of healthcare workers at various levels; the simplification of clinical guidelines (including clear guidance on screening, diagnosing, and treating common NCDs and risk factors); efforts to ensure the availability of affordable antihypertensive drugs; implementation of monitoring systems to ensure that drugs are available, accessible, and affordable; and monitoring of gaps in care as well as of population BP trends to inform and strengthen clinical and community interventions. Over the past decade, a number SSA countries have endorsed national hypertension programs.37 It is important that these programs comprise key features including multisectorial partnerships to develop and implement comprehensive primary prevention strategies (such as those aimed at reducing population added salt use), development and regular update of country-specific hypertension management guidelines, incorporation of simple care algorithms that may be part of more comprehensive NCD guidelines, setting up systems for monitoring and evaluation of efforts to prevent and control hypertension, and enlisting the support of national, international, and supranational organizations. Hypertension is a major public health problem in SSA. Its awareness, detection, and control are still suboptimal in SSA. Improved detection and management can prevent hundreds of thousands of strokes, myocardial infarctions, and premature deaths every year. Culturally tailored and innovative strategies to better prevent and manage hypertension are required. There is a need for improved systems of healthcare for widespread screening for hypertension and effective BP reduction and cardiovascular risk. A combined approach to lowering risk with societal, policy, and individual changes including lifestyle changes and the use of drugs within the framework of a much larger scale to prevent cardiovascular diseases is needed. None.