The state of hypertension in Africa: Insights into hypertension in Gambia

In 2023, the World Health Organization (WHO) reported the significant global impact on morbidity and mortality of hypertension and provided recommendations for combating this “silent killer”. The WHO estimates that over 1.3 billion people worldwide have hypertension, defined as a blood pressure (BP) of equal to or greater than 140 mmHg systolic and/or 90 mmHg diastolic. Unfortunately, the number of individuals with hypertension is increasing.^{1, 2} Of those 1.3 billion people with hypertension, it is estimated that 4 out of 5 of them are uncontrolled which yields a control rate of only 20%.^{1, 2} One study estimated that the average financial burden of hypertension is approximately $630.14 (US dollars) per person which approximates an $820 billion global financial burden.³ This clinical and financial burden is present even though there are safe, affordable, and effective pharmacologic treatments and evidence-based non-pharmacologic lifestyle modifications such as sodium reduction, weight reduction, and increased exercise. While most of the global data consists of data from low to middle income countries, it is important to acknowledge that hypertension control rates are not much better in high-income counties. Recent data from the United States, obtained prior to the COVID-19 pandemic, demonstrated that the hypertension control rate decreased for the first time from approximately 55% to only 45%.⁴ The WHO report also shows a global prevalence of hypertension in those aged 30−79 years to be about 33%. Regionally, and pertinent to this commentary, the prevalence of hypertension in the African region is estimated to be 36% of the general population.^{1, 2} The authors of this recent manuscript published in the journal have provided important new insights into the Gambian hypertension burden through the use of the cascade of care model.^{5, 6}

In the current issue of the journal, Jobe, Modou, and colleagues contribute an important manuscript which explores the current hypertension burden in The Gambia by obtaining data regarding average systolic BP, diastolic BP, and pulse pressure in each of the groups typically found in the care cascade. They also examined potential risk factors based on age, sex, and urban versus rural residence. Concerns regarding age arose due to recent data demonstrating that younger people with hypertension are exhibiting increasing hypertension-related target organ damage contributing to increased morbidity and mortality in this demographic group. In this study, a national representative sample of adults 35 years and older was identified using data from the 2013 Gambian Population and Housing Census along with information from a non-communicable disease survey embedded in the 2019 Gambian National Eye Health Survey.⁷ The authors were able to identify 11 127 potential participants of which 9788 agreed to participate in the data collection process. A total of 9171 people completed all aspects of the study and were included in the statistical analysis. Data collection included a questionnaire that evaluated the participants' age, level of education, marital status, occupation, area of residence, and socio-economic status. Participant height, weight, alcohol consumption, and smoking history were obtained, and a body mass index (BMI) was calculated. Finally, participants rested for at least 10 min before three BP values were obtained at 5 min intervals with the last two values being averaged together and used for analysis.

Using the patient data collected and a post-stratification weighting of participant characteristics, the authors were able to develop a cohort with equal proportions of men (4589, 50.0%) and women (4582, 50.0%) whose socioeconomic and demographic characteristics were stratified. Participants were also grouped based on their hypertension status into either normotensive, unaware, aware but untreated, or treated hypertensive groups. Hypertension was defined as a BP greater than or equal to 140 mmHg systolic and/or diastolic of 90 mmHg. The male population was found to have a higher proportion of normotensive and unaware hypertensive individuals while the female population had higher rates of aware but untreated and treated hypertensive individuals. The overall average SBP was 134.4 mmHg. Amongst the groups, the normotensive population average was 119.2 mmHg while the untreated, treated, and unaware hypertensive groups were 159.3, 152.2, and 148.7 mmHg, respectively. DBP showed a similar trend with the average DBP of the untreated, treated, and unaware hypertensive populations averaging 99.1, 95.1, and 93.9 mmHg, respectively. Of interest, males had a higher SBP regardless of their awareness or treatment status. SBP was higher in rural areas amongst the unaware population but showed no difference among the other cohorts. DBP was similar between rural and urban populations in all groups. Pulse pressures were also obtained and were shown to be lower in the normotensive groups with an average of 41.1 mmHg. Pulse pressures were wider amongst men but similar between rural and urban populations. Finally, the authors stratified all participants into either greater or less than 55 years old which revealed a significantly higher SBP in those > 55 years old, but no significant difference in DBP.

Based on the data collected during the study, the authors reinforce how critical increased surveillance, awareness, and education regarding the dangers of having hypertension are with a remarkable finding that almost 60% of hypertensive study participants were not currently receiving pharmacologic treatment. Furthermore, half of these individuals were unaware of their hypertension. It was also noted that a substantial number of the treated hypertensive individuals still had a BP greater than or equal to 140/90 mmHg. It was proposed by the authors that one reason for this high treated but uncontrolled rate was due to only those individuals with extremely high BP upon initial diagnosis receiving treatment, and the treatment was either ineffective or not intensified. Another reason for the poor control rate could be non-adherence with prescribed medications. It has been previously reported that approximately 73% of treated individuals with hypertension in The Gambia had stopped taking their medications.⁸ The authors theorized that other likely etiologies of treatment failures could also be due to medication side effects, local beliefs, or poor education on hypertension.

A strong consideration as a treatment intervention would be to use a standardized, straightforward, and simple pharmacologic treatment protocol/algorithm with timely follow-up periods and medication intensification. Included in the protocol/algorithm would be the recommendation to use two antihypertensive medications from complementary classes at half-maximal dosage upon the initial diagnosis of hypertension.⁹ Such recommendations are included in the recent WHO 2021 Pharmacological Treatment of Hypertension in Adults.¹⁰ The use of two antihypertensive agents from complementary classes has been shown to decrease BP equally in diverse patient demographics and to markedly decrease the racial BP control disparity rates in Black people compared to White people in the United States. While pharmacologic data is limited in the African population, some studies such as the Newer versus Older Antihypertensive Agents in African Hypertensive Patients trial (NOAAH) and the Comparison of Dual Therapies for Lowering BP in Black Africans trial (CREOLE) have shown that amlodipine-valsartan lowers BP to a greater extent than bisoprolol-hydrochlorothiazide (NOAAH),¹¹ and amlodipine-hydrochlorothiazide or perindopril-amlodipine lowers BP to a greater extent than perindopril-hydrochlorothiazide (CREOLE).¹² Another possible treatment intervention would be to improve the quality of medications provided to the region. One study demonstrated that when amlodipine and captopril were examined in sub-Saharan Africa, there was only 49.2% of measured to expected active ingredients.¹³

As with most studies, there are limitations. Limitations to the study which were recognized by the authors include that the study findings may not be generalizable to the Gambian populous because they only evaluated those > 35 years old. It was also a cross-sectional analysis of one data point while hypertension is typically diagnosed over several visits. They also recognized they only considered pharmacologic therapy as a “treatment” in their study participants and did not consider if those patients had made any lifestyle modifications as a way of management. Despite these limitations, this manuscript is important because it helps bolster our knowledge about an area where there is limited data regarding hypertension.¹⁴

In summary, research needs to continue and expand to help increase awareness, treatment, and control of hypertension especially in low to middle income countries. Furthermore, novel population-based interventions should be implemented to increase the effectiveness of hypertension management. Such interventions could include implementing the WHO Global HEARTS Initiative, the Pan American Health Organization HEARTS in the Americas Program, or the more recent Hypertension Clinical Pathway which strongly supports the expansion of a team-based approach to hypertension management.¹⁵ There is also merit in continued education of the general population to help overcome issues with nonadherence. As the burden of hypertension and its outcomes including heart disease and stroke continue to become more prevalent, it is imperative that investigations will continue to provide actionable data to improve the detection and management of hypertension.

Chandler Richardson: Writer. Sean J. Battle: Writer/Editor. Donald J. DiPette: Writer/Editor.