|Year : 2021 | Volume
| Issue : 1 | Page : 26-41
Hypertension in sub-Saharan Africa: A scoping review…
Jacques Joubert MB.ChB, MRCP (Edin.), FRCP(Edin.), FRACP, MD 1, Philippe Lacroix MSc, MD 2, Pierre-Marie Preux MSc, MD 3, Michel Dumas MSc, MD 3
1 Department of Medicine, Royal Melbourne Hospital, Melbourne, Australia
2 INSERM, University of Limoges, CHU Limoges, UMR 1094, Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST; Department of Thoracic and Vascular Surgery and Vascular Medicine, Dupuytren University Hospital, 2, Ave. Martin Luther King, 87042 Limoges, France
3 INSERM, University of Limoges, CHU Limoges, UMR 1094, Tropical Neuroepidemiology, Institute of Epidemiology and Tropical Neurology, GEIST, Limoges, France
|Date of Submission||01-Sep-2020|
|Date of Acceptance||13-Oct-2020|
|Date of Web Publication||27-Mar-2021|
Dr. Jacques Joubert
Department of Medicine, Royal Melbourne Hospital, Melbourne, Australia
Source of Support: None, Conflict of Interest: None
Like much of the developing world, sub-Saharan Africa (SSA) is facing a major challenge. This challenge is due to noncommunicable diseases (NCDs) whose rates are rising dramatically in SSA. Two conditions that frequently coexist head the list of NCDs as either established disease entities or risk factors for NCDs. These are hypertension and diabetes. Hypertension is the foremost cardiovascular condition. The objective of this scoping review is to examine peer-reviewed publications for the period 2009–2019 related to the detection and management of hypertension in SSA. We seek to define the issues confronted in managing hypertension in SSA, what measures have been implemented and evaluated, and what barriers and facilitators have been found. By mapping the complex, heterogeneous literature, we aim to identify the key concepts that underpin a major public health issue in SSA. The central question that this review addresses is how to control hypertension in SSA.
Keywords: Control, hypertension, management, sub-Saharan Africa
|How to cite this article:|
Joubert J, Lacroix P, Preux PM, Dumas M. Hypertension in sub-Saharan Africa: A scoping review…. J Clin Prev Cardiol 2021;10:26-41
| Introduction|| |
In sub-Saharan Africa (SSA) where infectious diseases have dominated health for decades, there has, in recent years, been an increase in the prevalence of noncommunicable diseases (NCDs). NCDs are, according to the United Nations Secretary General Ban Ki-Moon, a “public health emergency in slow motion” and the George Institute calls the rise of NCD in SSA a “looming epidemic.” Sir Seretse Khama Ian Khama at the 2017 State of the Nation Address in Botswana noted that “…deaths due to NCDs exceed those due to TB, malaria, and HIV combined.” Mortality aside, chronic disability is a major result of NCDs, and a recent review based on data from the Global Burden of Disease Injuries and Risk Factors Study (GBD) for the first time comprehensively examined the trends in disability-adjusted life-years (DALYs) in SSA. Between 1990 and 2017, the all-age rates for NCDs in SSA have risen by 67%. According to this report, the rates of DALYs for NCDs in all regions of SSA surpassed those in other countries worldwide. Cardiovascular diseases (CVDs) constitute the second-leading group of NCDs, and worldwide, 85% of cardiovascular (CVD) deaths are predicted to occur in low- and middle-income countries. NCDs in the developing world are coupled with an alarming shortage of health workers. In SSA, the uncontested leader as a risk factor for CVD and by implication for NCDs is hypertension.
| Methodology|| |
We performed a systematic search of the literature pertaining to hypertension limited to SSA and the years 2009–2019. We interrogated electronic databases with the assistance of the research librarian at the University of Melbourne. We used the electronic databases MEDLINE/Ovid and Scopus using keywords and MeSH strategy following guidelines developed for conducting a scoping review. We employed the system for Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA). We assessed article quality using the PEDro scoring method discarding articles with a score <6/10. We did not interrogate the grey literature. The results of the search strategy are shown in [Table 1] and [Table 2] as well as [Figure 1]. The initial research strategy included diabetes as well as obesity as these are often combined in articles regarding NCDs in SSA and would provide a good overall picture of NCD in SSA. This resulted in 162 articles. After removal of those articles where obesity and diabetes were the main focus, 81 articles remained where the main emphasis was on hypertension.
|Figure 1: Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA)(6).|
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| Results|| |
Prevalence and trajectory of hypertension in sub-Saharan Africa as a cause for concern [Table 3]
|Table 3: Selected articles demonstrating awareness, treatment, adherence and control of hypertension in SSA|
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As opposed to diabetes, the true prevalence of which is not known in SSA, the prevalence of hypertension has been well studied. Despite low initial assessments of hypertension prevalence in SSA, Ataklte et al. in a recent systematic review found a total pooled prevalence of 30%.
Bosu et al. in a systematic review of 34 studies found the overall pooled prevalence to be 57%. In rural South Africa, hypertension prevalence in a cohort of 5890 subjects was 58.4%.
Hypertension prevalence is rising in SSA while there is a decline in the developed world. Between 1990 and 2016, systolic hypertension in SSA increased by 82%. In Mozambique, between 2005 and 2015, the prevalence increased from 33.1% to 38.9% (P = 0.048). In Benin, the hypertension prevalence was 32.9% demonstrating a significant rise since a previous study prevalence being then 27.9%. Adeloye and Basqill estimated that 54.6 million persons had raised blood pressure (BP) in SSA, with an age-adjusted prevalence of 19.1%. This figure increased to 130.2 million cases in 2010 with an age-adjusted prevalence of 25.9%, projected to increase by 2030 to 162.2 million. In a landmark prospective cohort study in Soweto, CVD was found to be dominated by hypertension (56.3%) followed by heart failure (53.0%), with the second most frequent cause of heart failure being hypertension (33%). In Zimbabwe, in a cross-sectional hospital study, one in five hypertensive subjects had complications of hypertension such as cardiac failure.
In a Tanzanian hospital study of 11,045 consecutive admissions, hypertension resulted in 33.9% of NCD mortality. In South Africa, hypertension was in a calendar year cause of 46,888 deaths and 390,860 DALYs. Moreover, in Black South Africans, hypertension is more prevalent, more aggressive, and more difficult to control, with end-stage renal failure a common complication.
Standardized prevalence studies of hypertension in sub-Saharan Africa (2009–2019)
Amberbir et al. in a review of hypertension studies performed in Malawi noted four large studies, one being a WHO-STEPS approach to NCD surveillance. By 2016, a total of 39 WHO-STEPS surveillance studies had been performed in SSA. The WHO-STEPS protocol provides nuanced, standardized information. Cohort studies such as the TAnve Health STEPS Study examine the effect of population migrations and urbanization in SSA. In South Africa, a longitudinal cohort study is continuing in the Agincourt district of South Africa.
Nurse-led, protocol-driven interventions (2009 and 2019)
Good-quality randomized control trials in the period 2009–2019 are still rare [Table 4]. A Nigerian nurse-led, protocol-driven, two-arm randomized controlled trial achieved target goals at six months in 62% of rural and 70% of urban hypertensives, with a mean systolic BP reduction being 30 mmHg and 15 mm Hg for diastolic BP with adherence at 6 months of 77%. In the Cameroun, Kengne et al. achieved significant reductions in both systolic (11.7 mmHg) and diastolic BP (7.8 mmHg), (P < 0.001) reductions sustained over 6 months. Contrasting to the poor retention in this study, a cluster-randomized trial of nurse-led management in the Cameroun achieved retention of 60% and 65%, while in the control arm it was only 29%. A Nigerian prospective cohort study achieved a control rate of 64% and retention rate of >90%. A cluster-randomized Ghanaian trial preceded by a detailed exploration of stakeholders' attitudes and perceptions and training in hypertension management demonstrated a 85% retention and significant change (P = 0.021) in systolic BP at 12 months. Conversely, in a WHO-funded multisite study implementing nurse-led, protocol-driven hypertension management, 50% of subjects in the intervention group had persistently uncontrolled hypertension after 1 year. The Kenyan Sustainable model for Cardiovascular health by Adjusting Lifestyle and treatment with Economic perspective in settings of Urban Poverty (SCALE-UP) study demonstrated improvement in BP in the intervention group as well as the control group at the end of the study period, but no inter-group statistically differences. Retention to care was 28% of those referred and control of blood pressure only 9%.
|Table 4: Selected Randomized Controlled Trials performed in SSA between 2009 and 2020. Evaluated by PEDro and scored according to level 6 and higher in terms of evidence|
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Task-shifting to community health workers and pharmacists (2009–2019)
Five research projects relating to community health workers (CHWs) took place in SSA in the decade 2009–2019, two relating to training and supervision of CHWs while three investigating the impact of CHWs on NCDs.,,, Abegunde et al. tested a 3-day training package for CVD risk, finding an 80% concordance in all three areas (history and risk mapping, health behavior, and “treatment tracks”) between CHWs and medical doctors. In a similar project, Gaziano et al. examined whether CHWs could be trained in metrics such as the calculation of body mass index, taking BP with an automated machine, and accurately weighing a subject as well as applying a validated CVD risk score. CHW knowledge and skills at 3–6 months had increased from 40% pretest to 80.2% posttest with retention of knowledge of 75.3% on follow-up testing. Vedanthan et al. in the Linkage and Retention to Hypertension Care in Rural Kenya study described effective screening for CVD by CHWs using a smartphone with a decision-making algorithm to engage in a motivational and behavioral process. Kok et al. demonstrated group that supervision of CHWs in SSA was effective particularly when combined with a practical problem-solving focus. The perceived supervision scale promoting communication, bilateral decision-making, and contact for CHWs has been validated. Finally, CHWs delivering group health education resulted in significantly improved systolic and diastolic BP control. By contrast, in a pragmatic cluster-randomized trial in eight rural clinics evaluating the effect on BP where CHWs acted as a support for the clinic nursing staff, there was increased clinic attendance but no change in the rate of uncontrolled hypertension compared to control clinics without CHW support. Results of task-shifting to pharmacists were encouraging in Ghana, and in the Sudan, 70% of community pharmacists were willing to participate in hypertension education programs.
Interventions using mHealth for hypertension in sub-Saharan Africa (2009–2019)
In Cape Town a single-blind, randomized, three-arm trial testing short message system (SMS) messages designed to improve adherence in hypertensive patients demonstrated only minimal improvement in systolic BP at 12 months. Hacking et al. found no improvement in hypertension knowledge after 17 weeks of 90 SMS educative messaging to subjects with raised BP. Rotherham-Borus et al. reported a paradoxical raise in diastolic BP following an SMS supportive intervention. In contrast, Vedanthan et al. in a cluster randomized trial demonstrated statistically increased linkage to care by CHWs using mHealth. Sarfo et al. demonstrated the feasibility of using a Bluetooth-supported BP control in a study in Ghana.
Education of health professionals (2009–2019)
According to Folb et al., nursing staff in SSA often do not have adequate skills for NCD management such as hypertension. This was echoed by Mungati et al. .from Zimbabwe and Ogola et al. in Kenya. Encouragingly, Katende et al. implemented an innovative, culturally adapted WHO-ISH educational program for community nurses, resulting in significant improvement of knowledge, skills, and attitudes. Knowledge, in this study, increased from 62.8% pretest to 82.9% posttest while attitudes toward implementing evidence-based practices improved by 75%. In the Cameroun, intensive nurse education forms an integral part of the (current) nation-wide task-shifting initiative. Gyamfi et al. reported the results of the Task Shifting Strategies for Hypertension Control course that only 26.9% of nurses were “proficient” initially, while proficiency increasing to 95.7% at the end of the course. In Rwanda, a weeklong training program focusing on hypertension demonstrated significant increases in knowledge. Conversely, the Healthy Heart Africa project improved frequency of BP measurements but not knowledge of consequences of hypertension as compared to controls.
Similarly, a cluster randomized controlled trial in South Africa testing the effect of an education in 38 clinics reported no increase in treatment intensification and persistently poor control of BP after the education input.
Education of communities and patients (2009–2019)
In a Nigerian study, retirees exposed to an educational intervention based on the Information-Motivation-Behavioural model demonstrated improved medication adherence and knowledge of hypertension, the knowledge increasing significantly (P < 0.000) compared to controls. The Chronic Care Management model for hypertension employed in Matabeleland, Zimbabwe, used informal hypertension talks to transfer knowledge, an intervention that was shown to be effective. By contrast, a South African study testing mHealth as an educational tool with educational SMS messages did not improve knowledge of hypertension.
Participatory research and inclusion of communities (2009–2019)
Key to sustainability at primary care level is community involvement and ownership. Ajayi et al. using the Community Directed Interventions approach, evaluated what resources there were at community level in Southern Nigeria. Chimberengwa and Naidoo in Zimbabwe, reporting on a community-based participatory research project, noted that community-engagement aimed to combat hypertension has been reported in Ghana. In Rwanda, there is a comprehensive program working with stakeholders and communities to engage in participatory research based on evidence-based practices. Projects in Ghana, Zambia, and Western Kenya have successfully engaged with communities, patients, and stakeholders to better understand the facilitators, barriers, and perceptions regarding hypertension.
| Persistence of Poor Control of Hypertension in sub-Saharan Africa (2009–2019)|| |
Folb et al. studied the records of 3227 hypertensive attendees at 38 clinics. Of these, 59% of the patients' hypertension was uncontrolled. Maepe and Outhoff reported in 2009/2010 that in a cohort of 4297 miners in South Africa, only 42% were on treatment and 69% were poorly controlled.
BP control was achieved in only 52% of hypertensive patients in a Zimbabwean tertiary referral center. In Northern Tanzania, a rigorous study using random community-based sampling found that 95.3% of the subjects identified as being hypertensive had uncontrolled blood pressure. In a multinational study, blood pressure control ranged between 2.6% in Kenya and 18% to Namibia. A hospital-based cross-sectional study reported effective hypertension control in only 42.4% of subjects in Ethiopia. In Lesotho, only 21.4% of 70 hypertensive patients studied had their BP controlled. In Mafia Island, Tanzania, in just over half (57.6%) of hypertensives, treated control was achieved in only 20.6%. Among 2400 Ghanaians hypertensives, only 9% were on treatment and control was achieved in a mere 1.3%. Ataklte et al. performed a systematic review of hypertension in SSA between 2000 and 2013. Pooled data from 33 surveys in this review indicated that control was achieved in only 7% (95% confidence interval [CI], 5%–8%).
In our literature survey, only 10 publications addressed adherence and compliance as metrics. Only three studies employed the Morisky scale for medication adherence while one used the Hill-Bone compliance scale. In Nigeria, only one-third of hypertensive patients at both a specialty clinic and general outpatient clinic demonstrated high adherence. Nashilongo et al. in Namibia found that less than 50% of patients attending four peri-urban primary healthcare centers demonstrated adequate compliance in hypertension management. In the Cameroun, only 24.6% of hypertensives were controlled. In Ethiopia, over three hospital sites, despite good adherence to medication (67.2%), according to the Morisky medication adherence scale, 60% of subjects' BP remained uncontrolled.
| Barriers for Hypertension Control|| |
Patients' lack of awareness of hypertensive status
In the Cameroun, less than a third (31.7%), and in Nigeria, only 33.8% of people with elevated BP were aware of their hypertension. A systemic review by Ataklte et al. of 110,414 subjects found only 18% awareness present in pooled studies. In Namibia, more than half the subjects were unaware of the consequences of uncontrolled hypertension as well as the need for continued adherence to an antihypertensive medication regimen.
Lack of knowledge about hypertension and its consequences
An Ethiopian study of 278 hypertensive patients found that only 3.6% knew that hypertension was a risk factor for stroke. In the Gweru, urban district of Zimbabwe, Wariva et al. showed a significant association between knowledge and medication adherence (P = 0.001). Adherence to medication in the two facilities (university specialist clinic and a general outpatient clinic) studied by Akintunde and Akintunde in Nigeria differed significantly, ascribed to the more comprehensive educational input in the former. Price et al., implementing a diabetic educational program as the sole intervention, reported that at 18 months, the levels of HbA1c had fallen from 10.6 to 7.6 (P < 0.001) and were still significantly lower than baseline 4 years after intervention (P = 0.015). In the South African Masiluleke project, text messages with pertinent health information about HIV/AIDS and tuberculosis are transmitted daily to a total of one million mobile phones.
The barrier of cost and poverty
Wariva et al. found that adherence to medication correlated directly with even moderate differences in income. In a setting where medication was free, the level of nonadherence in this study was high (60%). Over 75% of patients lived more than 10 km from the health center, 66% being unable to afford paying for transport costs on a monthly basis. In the large population-based study in KwaZulu-Natal, 84.8% of the subjects were unemployed. In Nigeria, Ajayi et al. in eight communities (376,996 persons) reported that the majority of these had only access to well-water and in half the communities there was only one clinic serving on average 30,000 persons, most most paying out of pocket expenses for clinic services. In Nigeria, non-compliance with medication was attributed in 69% of cases to cost issues compared to only 6% related to drug side effects. Akintunde and Akintunde found that personal income was related to adherence. In Namibia, nonadherence was directly related to income. In Kenya, healthcarecost was, according to the Delphi ranking system, second only to accessibility of medication. This was poignantly recorded from a patient recorded to say “ No, I don't forget. I run out of medication…when I come, they say it's not there (medications), we go and buy, and you don't even have transport (funds) to travel. The other day I took a bit of my transport (funds) so I can buy some medicine…” (Vedanthan et al., 2016,P 318).
In Nigeria, 44% of the population in 2008 could neither read nor write. Awad et al. reported that 56% of women aged between 35 and 50 years and 34% of males aged between 35 and 50 years were illiterate. In Ethiopia, Desalegn et al. reported in a cross-sectional population-based study that 22.6% of 526 subjects could not read.
Josephs reporting on data from 770 hypertensive patients seen at the cardiology clinic at the University of Benin, Nigeria, found that the average number of medications per patient was 4.1 and compliance was 30.8%. By contrast, in a Kenyan slum, 99% of the patients took only one antihypertensive medication. In Ethiopia, only 20% of hypertensives were on three or more antihypertensive medications, and in the Western Cape, South Africa 15% of hypertensives were taking three or more medications.
Healthcare systemic factors and lack of medication and equipment
Poor linkage to healthcare services
After the identification of hypertensive status, linkage and retention are major issues. These relate to education, diagnosis acceptance, and physical factors such as transport, distance, and cost. In Western Kenya, linkage and retention remain significant problems. Siedner et al. in KwaZulu-Natal demonstrated that in a large population-based cohort study (2010), after screening at home, of 1706 hypertensives not previously identified, at 2 years of follow-up, only 26.9% had sought and obtained treatment, and after 5 years, this figure dropped to 38.1%.
Clinic and healthcare center processes and issues
The physical lack of sphygmomanometers and suboptimal flow of medication has been a factor mentioned repeatedly in the literature. The experience of patients at primary healthcare facilities is waiting, often for hours before seeing the health professional, only to find medication unavailable.
Factors related to medical and nursing personnel
Lack of knowledge and suboptimal approach to management of noncommunicative diseases by health professionals
In a study of South African primary care 16 doctors, only 10 stated that they would treat hypertension to target and only two knew the South African hypertension guidelines which had been displayed in the two clinics where the study took place. A study by Ogola et al. provided important insights into the complexity of nurse training reporting on the results of Healthy Heart Africa, a program including provision of a training manual, hypertension management algorithm, access to medications through a pharmaceutical company as well as to equipment. At 12 months, there was improved knowledge and behavior of health providers relating to hypertension, but no change in their knowledge of the consequences to hypertension. In fact, the control group more frequently, on questioning, identified sequelae such as death, heart attack, and stroke than the intervention group.
Clinic nursing staff overwhelmed, on the edge of “burn-out,” lack of support
Katz et al. described the South African Chronic Disease Outreach program and its challenges. Feedback from nursing staff employed in this model were “they remained concerned about litigation;” “having responsibility without the authority to act;” “frustration at being overworked and that doctors do not respect the role they play;” “no doctors to help with up-scaling of medication;” “.nurses/PHCNs were constantly rotated through different areas and never allowed them time to develop confidence in managing chronic diseases”; “… not very confident”. The study revealed the staff in the Chronic Disease Outreach program as being exhausted, lacking support, lacking adequate training, and experiencing frustration.
Poor attitude of medical and nursing staff toward patients
The need for a more patient-centered, education-supported model was found by Murphy et al. in the South African study which examined hypertension as one of several noncommunicable conditions from a patient's perspective. This qualitative study was based on and guided by the principles of self-determination, which is in line with the approach advocated by the WHO which emphasizes the need to increase the knowledge base and the motivation of patients. Hypertensive patients' recurrent themes relating to health provider attitudes were as follows: “no time,” “no emotional support,” no inclination to explain,” “impatient,” “rude,” and having questions but feeling apprehensive about asking.” The traditional healers understand the culture and the needs of the population and are able to “tap” into that. In particular, they provide patients with reasons for their condition.
| Conclusions|| |
In the last decade, there have been significant positive achievements related to hypertension across many domains. Studies have been made of hypertension prevalence using the WHO-STEPS methodology as well as other models of population surveys such as on Mafia Island in Tanzania and the HAALSI project in Agincourt, South Africa. These have demonstrated the feasibility of obtaining accurate, repeatable population-based data, in SSA. Studies testing task-shifting from doctor to nurse-led management have yielded positive results and in some studies excellent adherence. Positive results have been demonstrated in nurse education. Increased training, supervision, and deployment of CHWs have been done., Despite these positive steps, detection, awareness of being hypertensive, having treatment, and achieving control of hypertension in SSA continue to remain suboptimal. Dramatically, different results are documented. For example, excellent hypertensive control such as in reported by Ademoye et al. This can be compared to the study by Mendis et al. where control was very poor. The high early drop-out figure reported by Kengne can likewise be compared to the high retention of patients reported by other authors. Possibly, answers may arise through the analysis of two recent community-based interventions for hypertension management, one in Africa and the other outside Africa., The findings in these two well-constructed studies were substantially different. The SCALE UP intervention was intense and included an awareness (radio) program, monetary incentives to CHWs, and text (SMS) messages for appointments and taking of medications; however, at the end of the study period there was no difference compared to controls. The HOPE 4 intervention, conducted in Bolivia and Malaysia included medical support from physicians, support from family members and tablet computer-based simplified algorithms for treatment, the latter managed by CHWs who liaised with physicians. There was a significant difference in hypertension control in the intervention group. The answer to future effective models of hypertension care may lie in subtle system-based differences in approach.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]