Hypertension in sub-saharan africa, how to address this rising pressure

PHOTOS SHUTTERSTOCK

Noncommunicable diseases (NCDs) (predominantly cardiovascular diseases (CVDs), diabetes, cancer and chronic respiratory diseases) are increasingly becoming a looming threat that is creating a double burden in low- and middle-income countries (LMICs). The high-level meeting on NCDs at the General Assembly of the United Nations in 2011 clearly underscores how NCDs now dominate the health agenda worldwide(1). This is rightly so because more than 60% of preventable deaths worldwide are now attributable to NCDs. In LMICs, 48% of such deaths occur in persons <70 years of age, compared with 26% in high-income countries(2-4). In sub-Saharan Africa (SSA) where infectious diseases are still the overall leading cause of death, the incidence of NCDs is increasing rapidly, a region in which urbanization and population growth are most extreme. In 2008, the age-standardized NCDs mortality rates for all ages were highest in the WHO African Region compared with the overall NCDs age-standardized death rates in LMICs(4). CVD is the second leading killer overall and the leading cause of death among adults aged 30 years and older, who are in their most productive years of life in SSA(3).

Hypertension is a major risk factor for CVD and it is increasingly becoming a major health burden in SSA (5,6). During the first half of the twentieth century hypertension was real in sub-Saharan Africa (SSA), but estimates now show that in some settings in SSA more than 40 percent of adults have hypertension(7). The estimated 80 million adults with hypertension in SSA in 2000 are projected to rise to 150 million by 2025(8).

Relevant drivers and implications

As socio-economic development in SSA societies continues, hypertension is expected to become more prevalent, particularly in urban populations. The increasing prevalence of hypertension and its related sequelae are driven mainly by changes in environmental and behavioural determinants associated with socio-economic development and prolongation of life expectancy. Whereas European and North American populations experienced similar changes in demography, determinants, and disease rates over the course of a century, SSA populations are passing through similar transitions in just a few decades(9).

A major reason for the increase of hypertension rates in SSA is due to the high urbanization rate. Currently 395 million, almost 40 percent of the total population in SSA, live in urban areas(10), but this is projected to grow to one billion in 2040, and to 1.23 billion in 2050. The levels of hypertension are structurally higher in urban than in rural settings (11,12) mainly because of contextual and behavioural factors associated with urban environments such as dietary changes and sedentary lifestyle that together form a complex system conducive to developing hypertension(13). An increase in hypertension prevalence will invariably lead to dramatic rises in the incidence of CVDs, which has the potential to overwhelm health care systems (14,15). It will also have financial implications for national and local treatment plans because there is increasing evidence that the majority of patients with hypertension will require two or more drugs to achieve adequate blood pressure control(16).

Prevalence of hypertension in ssa

Hypertension prevalence in SSA varies widely across countries. Reliable, large-scale, population based data on hypertension in Africa is scarce (17). The WHO STEPS survey conducted between 2003 and 2009 in 20 African countries reported high rates of hypertension in most countries, particularly among men. The prevalence ranges from 19.3% in Eritrea to 39.6% in Seychelles (18). In all countries where data is available from the World Health Study (WHS), the urban population has a higher prevalence of hypertension than the rural population, with South Africa and the Democratic Republic of Congo leading with almost 10 percentage points higher prevalence than the rural population. The huge differences in hypertension prevalence rates across SSA countries are probably due to variations in social economic development, cultural factors and the degree of adoption of unhealthy life styles across SSA countries.

It is well-known that urban averages mask great intra-urban disparities largely due to the presence of large populations in poor slum settlements that characterize most urban centres in Africa. Data from Nairobi collected from the adult population in two slum settlements (19) shows a high prevalence of hypertension (overall of 19%) with large sex and age-specific differences.

Challenges of awareness, treatment and control of hypertension in ssa

The low rates of awareness, treatment and control of hypertension in SSA are a major public health concern(20). The low levels of these indicators are present in almost all settings on the continent and imply that there will be large populations of hypertensive patients unaware of their increased risk of hypertension-related complications in the coming years. A possible contributory factor to these worrying data could be the affordability of health care, which remains a major barrier in the African setting as out-of-pocket spending is the main source of funding for health care costs (21).

Another challenge that is prevalent all over SSA is the non-adherence to treatment and follow-up for hypertension. In one intervention study in Cameroon, for instance, just about half of the participants were still in the programme at one-year follow-up(22). Indeed, patients are expected to be treated and controlled only if they can access appropriate health services, receive adequate advice and prescriptions and subsequently can afford and adhere to those prescriptions. Increasing awareness, treatment and control rates of hypertension will have a huge impact on CVD prevention in Africa(23). Whereas in Africa often only 5 to 10 percent is controlled at a blood pressure of less than 140/90 mmHg(11,24,25), there are also studies from South Africa showing rates of control increasing from 48.4% in 2007-2008 to 53.3% in 2009-2010 indicating that with major efforts, improvement in hypertension control can be made in other SSA countries.

Interventions to address this rising pressure

In SSA, providing medication is considered an important and cost effective way to reduce hypertension (26), but accessibility to and cost of the treatment are very often forgotten. Currently, African countries are 80 percent below the global average for pharmacological spending and 20 percent below the global average of behavioural risk factors for hypertension(27).

The efficacy of blood pressure lowering medications is well demonstrated and treatment of high-risk individuals has been advocated as a major strategy for CVD prevention in all regions, including Africa (28). However, the problem of defining a strategy for hypertension control confronts most societies(29). Hypertension is fully treatable, but social and economic conditions in many African countries make the implementation of blood pressure control programmes difficult. Lack of a clear strategy based on evidence has undermined these efforts further. Inadequate funds, inexperience, and lack of infrastructure remain important barriers to hypertension detection and treatment(30). Accordingly, the overall management of hypertension is as much a socio-economic as it is a therapeutic problem. Screening ideally not only detects hypertension but also forms the basis for education and therapy.

Finding practical solutions for prevention of hypertension in SSA is an enormous task that is achievable only through collaboration. An active approach to hypertension must be driven by the ministries of health as well as by local organizations, with support from influential bodies such as the International Forum for Hypertension Control and Prevention in Africa. The current enthusiasm for collaboration is crucial for the development and implementation of health care policies throughout the region.

Further references on our website: www.nvtg.org

References

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