Abstract

Background This study was undertaken to describe the prevalence of hypertension among the black populations of Africa, the Caribbean, and North America. Methods A search was made using grey literatures and major electronic databases including PubMed, Cochrane, Google Scholar, and Embase for population-based studies published between January 1, 2017 to September 15, 2022, reporting the prevalence of hypertension for adults aged ≥ 18 years living in Africa, the Caribbean, and North America. A random effects model to estimate the pooled prevalence across included studies was employed. Findings A total of 6,779 articles were screened and 351 full-text articles were obtained to assess for inclusion in this review. A total of 274 unique studies with 186 data points in all 28 African countries, 13 Caribbean, and 5 North American countries recognized by the United Nations were reviewed. The prevalence of hypertension in Africa ranged from 23.3 to 42.0%, in the Caribbean, it ranged from 26.5 to 48.8% while in North America, the range was 31.7 to 54% from individual studies. The overall percentage was 32.6% in Africa, 37.6% in the Caribbean, and 42.8% in North America. Prevalence did not differ statistically by sex, place of residence, African, Caribbean, or American subregion. In separate studies, older age and overweight or obesity were independently associated with hypertension. Overall, the GRADE assessment suggested moderate quality evidence in the results. Conclusion There is a high prevalence of hypertension in the populations of North America, the Caribbean, and Africa. This is true of both urban and rural areas.

1. Introduction

Hypertension (HTN) stands as a formidable global health challenge, affecting an estimated 1 billion individuals worldwide. With its prevalence steadily rising, HTN represents a significant risk factor for adverse cardiovascular events, including strokes, heart attacks, and kidney failure ^{1, 3} Notably, its impact is disproportionately felt among black populations in Africa, the Caribbean, and North America, where historical associations with cardiovascular disease have contributed to alarming mortality rates, particularly among those over 40 years of age ⁷.

In Africa, the burden of HTN is starkly evident, with approximately 900,000 deaths attributed to the condition in 2016 alone. This marked an 82% increase since 1990, reflecting both the growing prevalence of HTN and its dire consequences ^{9, 12}. Sub-Saharan Africa, in particular, grapples with an overall prevalence of approximately 30.8%, as reported by the Framingham study. Alarmingly, the study predicts that 90% of normotensive individuals who live to the age of 55 will eventually develop HTN, highlighting its pervasive nature across diverse demographic groups, including rural populations, impoverished households, and younger individuals ⁵.

Similarly, the Caribbean and North America face escalating rates of HTN, driven in part by the obesity epidemic and the aging population. Despite concerted efforts, only about 30% of individuals with HTN in North America have their blood pressure under control, indicating significant gaps in effective management strategies. This underscores the multifactorial nature of HTN risk, which is intricately linked to age, weight, and ethnicity. Notably, black individuals, the elderly, and those with diabetes exhibit the highest prevalence rates, further exacerbating disparities in disease burden and healthcare outcomes ¹⁷.

Efforts to address the HTN epidemic are hindered by various systemic challenges, including limited access to quality healthcare services, poor treatment adherence, and inadequate provider interventions. Furthermore, the economic burden of HTN is staggering, with the United States alone spending an average of $131 billion annually on treatment costs ⁴. This financial strain is compounded by the substantial human toll, with HTN accounting for more than half of early acute strokes in the USA, Africa, and the Caribbean, in addition to emerging as a potential modifiable risk factor for dementia. In response to these challenges, there arises a critical necessity for the implementation of comprehensive prevention and control measures tailored to the distinct requirements of affected communities ^{1, 9}. This imperative encompasses augmenting access to high-quality healthcare services, advocating lifestyle adjustments to mitigate hypertension risk factors, and executing focused interventions to alleviate disparities in disease burden and healthcare outcomes. By prioritizing the prevention and management of hypertension, particularly among vulnerable demographics in Africa, the Caribbean, and North America, we can mitigate the dire consequences of this global health crisis and enhance the overall health and well-being of impacted individuals and communities ³⁵.

Despite concerted efforts to tackle this issue, there persists a dearth of comprehensive understanding regarding the prevalence and management of hypertension within these regions. This review aims to address this gap by systematically analyzing current population-based studies published between 2017 and 2022. Through elucidating the prevalence and associated factors of hypertension among black populations, this study endeavors to identify disparities in disease burden and healthcare outcomes, thereby informing targeted interventions and enhancing overall health outcomes ³⁸. However, it is important to clarify that the primary objective of this study is to investigate the prevalence of hypertension among black populations and conduct an exhaustive review spanning Africa, the Caribbean, and North America.

2. Method

Exclusion and Inclusion Criteria:

The methodology employed in this study was designed to ensure the selection of relevant and high-quality research studies. We included cross-sectional or follow-up studies reporting the prevalence of hypertension (HTN) among adults aged 18 years or older residing in Africa, the Caribbean, and North America ^{38, 41}. These studies were required to have been published between January 1st, 2017, and September 15th, 2022. HTN was defined as a blood pressure meeting or exceeding the threshold of 130/80 mmHg or by subjects receiving antihypertensive therapy, regardless of their blood pressure at the time of measurement. This definition aligns with the guidelines established by the American College of Cardiology and the American Heart Association in 2017 ⁷. Individuals excluded from the study were pregnant, admitted to the hospital, or diagnosed with chronic mental health disorders. Additionally, articles featuring immigrants residing outside the specified regions and review articles were excluded to maintain the focus on the targeted populations.

Search Strategy:

A systematic and comprehensive search strategy was employed to identify relevant literature from multiple sources. Major electronic databases, including PubMed, Embase (via Ovid), Academic Search Complete, CINAHL, Springfield College Library Database, and PsycINFO (via EBSCOhost), were searched. Additionally, the African Journals Online repository and Google Scholar were queried to capture a diverse range of studies. Manual searches of references from included studies were conducted to identify additional relevant articles. Gray literature was also searched using Open Gray and ProQuest in addition to the electronic databases mentioned earlier. The search strategy involved the use of a combination of keywords and controlled vocabulary terms related to population, statistics, distribution, epidemiology, hypertension, blood pressure, cardiovascular, and cardiometabolic. The search was limited to studies conducted in Africa, the Caribbean, and North America to ensure relevance to the specified regions. Within each concept, the terms were linked using the 'OR' operator, and the results across concepts were combined using the 'AND' operator to refine the search results. Furthermore, the search was restricted to human studies conducted in middle age (ages 18-64) or in old age (ages 65+) to target the appropriate demographic. Key terms such as "middle-aged adult," "middle-aged elderly," and "senior" were used to filter the results accordingly. The Covidence software was utilized to manage search results and automatically identify and remove duplicate papers. Inclusion and exclusion criteria were applied to titles and abstracts to screen for eligible studies efficiently. Keywords such as 'patient' and 'pregnant' were used to facilitate rapid review and exclusion of ineligible studies based on the defined criteria. Multiple papers published on the same subject sample were counted as one study to avoid duplication and ensure accuracy. Supplementary data were obtained from additional reports when required to enhance the completeness of the review. Studies estimating HTN at different time points in the same cohort were counted as separate studies to capture variations in prevalence over time. Similarly, studies that included multiple countries in Africa, the Caribbean, and North America were counted as studies providing multiple data points, corresponding to the number of countries included in the study.

Data Extraction:

Data extraction was conducted meticulously to ensure the accurate capture of relevant information from the selected studies. Data were extracted onto a preformatted tabulated Table 1 Table 2 Table 3 Table 4 Table 5 Table 6 and Table 7, which included essential details such as the study's primary author, year of publication, setting, socio-demographics, study population characteristics, risk factors associated with HTN, and the prevalence of HTN reported in each study. This comprehensive approach to data extraction facilitated the systematic organization and analysis of key study characteristics and outcomes.

GRADE Assessment of Overall Quality of Evidence:

The Evaluation of Recommendations, Development, and Evaluation (GRADE) methodology was employed to assess the overall quality of evidence derived from the included studies. GRADE is a widely recognized approach that adapts standards for evaluating systematic reviews of prognostic research, providing a structured framework for assessing the reliability and validity of review estimations. Five key areas were considered within the GRADE assessment framework: risk of bias, imprecision, inconsistency, indirectness, and publication bias. Each area was systematically evaluated to determine its impact on the overall confidence in the pooled estimate. Confidence levels were assigned based on the degree of confidence in the pooled estimate's approximation to the genuine population estimate. A "high" level of evidence indicated a high degree of confidence in the pooled estimate's accuracy, while a "very low" level of evidence suggested a lack of confidence. Intermediate rating ranges, including "middle" and "low," were assigned based on the assessment of the identified factors. Confidence increases were considered estimates, providing valuable insights into the reliability and validity of the review findings.

The implementation of these methodological steps ensured the rigor, validity, and reliability of the study findings, thereby contributing valuable insights into the prevalence and management of hypertension among diverse populations in Africa, the Caribbean, and North America. This systematic approach facilitated the identification of relevant literature, extraction of key data points, and assessment of overall evidence quality, ultimately enhancing the credibility and significance of the study results.

3. Data Analysis

The overall pooled prevalence across studies was estimated using a tabulated random table to summarize the prevalence of HTN in Africa, Caribbean, and North America.

We assessed the prevalence among the population of Africa, Caribbean, and North America excluding studies deemed to be at high risk of bias on the pooled estimate. We performed an influence analysis by computing the summary estimate of the prevalence of HTN after removing one included study at a time.

4. Results

Research flow and characteristics.

After title and abstract verification, 651 full-text articles were retrieved and evaluated for inclusion. Two hundred and twenty-six 226) of these full-text articles were excluded for various reasons. Self-reported HTN estimates or not estimating HTN prevalence were not used at all. Of the remaining 274 eligible full-text articles, 121 individual studies published between 2017 and 2022 were retained for analysis after reviewing multiple studies on the same research topic. Forty-two of these studies included multiple countries or cohorts and provided a total of 37 statistics studies. Sixty-four studies (21.7%) were published in 2017-2018, ninety-one (82.9%) in 2019-2022.

5. Discussion

The results of this review show that HTN is common in North America, the Caribbean, and Africa, with average respective prevalence rates of 42.8%, 37.6%, and 32.6%. Furthermore, we found that the prevalence rates in Africa, the Caribbean, and North America differ considerably. Despite the different numbers of studies in each subgroup, there are differences between data collected in the community and those done in hospitals. Our research indicates that people in North America have the highest rates of HTN both in hospital and community settings. However, North America offers the population the greatest methods for managing and controlling HTN.

In comparison to North America, the Caribbean and Africa have lower prevalence rates and subpar management. WHO conducted studies that showed North America has the best clinical management of HTN ³. Smoking, a high-salt diet, and alcohol usage are the major contributors to the development of HTN in Africa and the Caribbean. However, in North America obesity is the major factor. Our prevalence findings of HTN, which vary between 42.8%, 37.6%, and 32.6% respectively, are slightly greater than what was observed for the World Health organization survey in 2016. Because they have African ancestry, Agyemang et al. demonstrated that there may not be a significant difference in the prevalence of Africa and the Caribbean. In North America, non-Hispanic black adults (40.3%) had a greater prevalence of HTN than non-Hispanic white adults (27.8%), non-Hispanic Asian adults (25.0%), and non-Hispanic adults (27.8%) ⁴. Generally speaking, adults had a 31.4.0% prevalence of HTN overall, with males (30.2%) and women (27.7%) having similar rates ¹³. In individuals aged 18 to 39, the prevalence of HTN was 9.5%; in those aged 40 to 59, it was 36.4%; and in those aged 60 and above, it was 63.1%. Both men and women showed the same tendency. Men had a lower prevalence of HTN than women among adults 60 and above (59.6% compared with 68.9%, respectively), but men had a greater prevalence of HTN among people aged 18 to 39 (9.2% compared with 5.6%, respectively) and 40 to 59 (37.2% compared with 29.4%, respectively).

Our data suggest that more than two out of every twenty people in Africa are hypertensive yet do not seek treatment ⁹. Our data present an overwhelming image of poor care in Africa and fair clinical management in the Caribbean due to the high prevalence of HTN in these regions. Most patients in North America (except those in the lower socioeconomic groups) have access to good quality medical care. Additionally, they can have lifetime treatment to keep their blood pressure within normal limits. However, awareness is a key element in the effective management of HTN. Africans are less aware than other people, which makes them less likely to seek medical treatment ²⁹. Even those few who do understand this problem find that high-quality healthcare is either extremely difficult to obtain or prohibitively expensive, which is devastating for the continent's population ³⁰. Furthermore, cardiovascular disease has a high mortality rate in Africa. According to the International Database on Ambulatory Blood Pressure in Relation to Cardiovascular Outcomes (IDACO) study, this is because the continent lacks awareness of the condition and access to high-quality healthcare. In contrast, a recent investigation ³⁴, which in some respects confirmed the results of the meta-analysis by Briasoulis et al., discovered that individuals who were unaware of their hypertensive status were likely to experience an increased risk of cardiovascular disease and overall mortality. To protect Africans from the high prevalence rate of HTN, the general public needs to be made aware of the dangers of untreated HTN and it’s necessary to be aware of the controlling principles. According to WHO recommendations, the healthcare systems in both Africa and the Caribbean need to be improved to cope with the increased rates of HTN.

The shocking finding of our literature review was that more than 4 in 10 people in North America had been aware of the dangers of HTN ⁶. In fact, there is a good understanding within the US population that people with HTN are more likely to suffer from kidney disease, cardiovascular illness, and target organ damage ¹⁹. Therefore, there is a need to raise HTN awareness across Africa and the Caribbean. The first and most glaring flaw was that several included studies that looked at patient care disclosed different diagnostic techniques and BP device usage over the course of the study. This increases the variability in our findings. But a limitation must be considered to fully comprehend these results ⁵. To the best of our knowledge, this is the first comprehensive review of literature that enumerates the most recent studies on the prevalence of HTN among blacks in North America, the Caribbean, and Africa. With the use of methodological and statistical techniques, we exhaustively searched the major electronic databases and discovered 274 studies with a low to moderate risk of bias.

6. Conclusion

This study highlights the fact that HTN is highly prevalent in North America, the Caribbean, and Africa. North America had the highest prevalence of HTN compared to others. This discovery has implications for public health as increasing prevalence will lead to a high risk of other cardiovascular diseases ². It was also discovered that many individuals with HTN in Africa and the Caribbean were unaware of the dangers of having uncontrolled HTN. This emphasizes the necessity for quick measures to spread awareness and put into action strategies for the early diagnosis and treatment of HTN, particularly in people under 35 years of age and there is a need to target those who are obese/overweight.

References