Feasibility of a cardiovascular cohort in a Sub-Saharan Africa community: preliminary report of the pilot project TAHES (Tanvè Health Study) in Benin

Hypertension in sub-Saharan Africa: the current profile, recent advances, gaps, and priorities

Recent global and regional reports consistently confirm the high and increasing prevalence of hypertension in sub-Saharan Africa (SSA), with poor detection, treatment, and control rates. This narrative review summarises the burden of hypertension in SSA and recent findings from community-based hypertension management strategies. We further outline prominent risk factors according to recent data and associated underlying mechanisms for hypertension development. An extensive review of literature showed that most countries have reported on the prevalence of hypertension during 2017-2023, despite limitations linked to the lack of nationally representative studies, heterogeneity of sampling and data collection methods. Task-shifting approaches that assign roles to model patients and community health workers reported improved linkage to healthcare services and adherence to medication, with inconsistent findings on blood pressure (BP)-lowering effects over time. The regularly reported risk factors include unhealthy diet, sedentary lifestyle, increased adiposity and underweight, ageing, level of education, and/or income as well as psychosocial factors. Newer data on the pathophysiological mechanisms leading to hypertension and potential areas of intervention are reported from children and adults and include, among others, salt-handling and volume overload, endothelial function, BP dipping patterns and the role of human immunodeficiency virus . To conclude, significant strides have been made in data reporting from SSA on the burden of hypertension in the region as well as biomarker research to improve understanding and identification of areas of intervention. However, gaps remain on linkage between knowledge generation, translation, and implementation research. Coordinated studies addressing both discovery science and public health are crucial to curb hypertension development and improve management in SSA.

Informal Care Time and Costs of Dementia Care in Benin (West Africa)

BACKGROUND

Dementia is a growing global health challenge, with significant socioeconomic implications. This study examined the informal care duration and related costs along with the total cost of care for older individuals with dementia in Benin, West Africa, providing insights into a region with limited dementia research.

METHODS

We conducted a cost-of-illness study in Benin. Both hospital and community recruitments were used to enroll adults aged ≥60 years and their primary caregivers. Structured questionnaire and validated tools were used to collect the demographic, clinical, healthcare resource utilization data as well as informal care duration. Replacement costs approach was performed to valuate informal care time. Official exchange rates from the World Bank were used to convert costs from local currency to purchasing power parities dollars (PPP$).

RESULTS

Data from 135 individuals with varying dementia stages revealed that dementia places substantial caregiving demands, predominantly on women who provide up to 8 h of daily care. In 2021, the mean annual cost of dementia care was estimated to be PPP$ 2,399.66 ± 2,057.07. Informal care represented a significant portion of dementia expenses, up to 92% of the total care costs in this study.

DISCUSSION

Policy interventions are urgently needed to address the dementia care challenges in Benin, especially because economic transitions and educational advancements may reduce the availability of informal caregivers. This emphasizes the vital role of informal caregivers and underscores the need of implementing dementia policies to support families facing the evolving challenges of dementia care.

Normal reference values of cardiac chamber sizes and functional parameters in a beninese community population: the TAHES study

Reported ranges of normal values for echocardiographic measurements are mostly issued from studies performed in Caucasians. This study is a part of TAHES, a population-based prospective cohort study in Benin and aims to establish normal reference values for echocardiographic cardiac chambers dimensions and Doppler parameters in a Sub-Saharan African population. We included 486 healthy (non-diabetic, non-obese and normotensive) individuals (202 men and 284 women, age 37[30-47] years, BSA 1.58 (1.47-1.67) m2). End-diastolic interventricular septal wall thickness, left ventricular (LV) internal diameter, posterior wall thicknesses, and systolic LV internal diameter were respectively at 10[9-12], 45[43-49], 9[8-11], 29[26-34] mm for male and 9[7-10], 43[41-46], 8[7-], 29[27-32] mm for females. LV mass was significantly greater in males even after normalization for the body surface area (98[85-117] vs. 82[71-96] g/m2). Upper limits of BSA-indexed LV mass were 145 g/m2 for males and 124 g/m2 for females. The allometric exponent that described the LV mass-Height relationship were 2.5 in both sexes but 1.2 for males and 1.8 for females separately. E-wave velocity was 0.79 [0.65-0.90] cm/sec in males and 0.88 [0.78-0.99]cm/sec in females (p < 0.0001) but without significant gender differences in E/A ratio (limits: 0.75 and 2.1). The e'-wave velocity (lower limit = 8 cm/sec) decreased and E/e' ratio (Upper limit = 9) increased with aging. Upper limit of BSA-indexed left atrium volume was 38 mL/m2 for both sexes. In conclusion, normal values from a general population in West Africa differ from those established in Caucasian populations with greater LV mass and wall thicknesses.

Cardiovascular risk factors in Sub-Saharan African women

Summary: Background: Cardiovascular risk factors (CVRF) are associated with major cause of death and disability in Sub-Saharan Africa, especially in women. The contribution of obstetrical, psychological, and socio-economic factors in CVRF are not yet well described in Africa. We aimed to compare the prevalence of CVRF between men and women, and to determine the factors associated to these sex-related differences. Patients and methods: A cross-sectional study was conducted on the 2019 data of the TAHES cohort in a geographically defined general population in Benin. A standardized questionnaire adapted from the World Health Organization (WHO) STEPS instrument was used to collect data. Univariate and multivariate analysis has been performed to determine CVRF differences in both sexes. Women-specific logistic regressions have been performed on CVRF previously identified as positively associated to female sex, to assess their association with socio-economic, psychological, and obstetrical factors. Results: We included 1583 patients, with a median age of 39 years [range: 32–53 years]. Prevalence of diabetes (1.2% vs. 3.4%, p=0.0042), abnormal kidney function (15.5% vs. 8.4%, p=0.0002), obesity (12.5% vs. 4.1%, p<0.0001), tobacco-smoking (3.4% vs. 14.1%, p<0.0001) and reduced physical activity (69.9% vs. 50.7%, p<0.0001) differed significantly between women and men, respectively. In multivariate analysis, female sex was independently and significantly associated with obesity, anxiety, depression and reduced physical activity. Number of pregnancies was associated with a reduced physical activity. Hypertension was associated with gestational hypertension. Conclusions: Obesity and reduced physical activity are significantly and independently more frequent in Beninese women than the male counterparts. Hypertension prevalence in Benin is alarming in both sexes. Targeted prevention strategies against obesity, gestational hypertension and sedentary lifestyle are advocated in African women.

Normal limits of electrocardiogram in Africans and their consequences on the prevalence of left ventricular hypertrophy in hypertensive individuals: Insights from the TAHES study

AIMS

To determine normal limits for major ECG variables, and the electrocardiographic impact of hypertension, in a rural sub-Saharan African setting.

METHODS

This cross-sectional study included adults aged ≥25 years from Tanvè Health Study (TAHES) cohort. ECG were recorded at rest at 25 mm/s using a standard 12‑lead device. Wave amplitudes and durations were measured. Corrected QT interval (QTc) was calculated using Bazett's formula. Sokolow-Lyon, Cornell and Peguero-Lo Presti criteria were determined to assess left ventricular hypertrophy (LVH).

RESULTS

ECG was recorded among 997 out of 1407 TAHES participants. After exclusion of subjects with hypertension or diabetes, normal limits, defined as the 2nd and 98th percentiles, were evaluated in 622 healthy participants (median: 37 years; 60.1% women). The following limits were established in men (women): heart rate: 50 to 100 (55 to 102) beats/min, P wave duration: 80 to 120 (80 to 120) ms, PR interval: 120 to 200 (120 to 200) ms, QTc: 315 to 470 (323 to 465) ms, QRS duration: 50 to 120 (50 to 110) ms. Upper limits (in millimeter) for the Sokolow-Lyon, Cornell and Peguero-Lo Presti for men (women) were 47 (38), 30 (22) and 39 (30), respectively, all above current reference limits. The prevalence of LVH in hypertensive subjects according to these criteria were lower than those estimated according to current LVH criteria.

CONCLUSION

The normal limits of ECG variables determined in this African population differ from those in Caucasians, indicating that ethnicity must be considered in ECG interpretation.

Prevalence of sleep-disordered breathing in an African general population: The Benin Society and Sleep (BeSAS) study

BACKGROUND

Data on the prevalence of sleep-disordered breathing (SDB) in the African general population are scarce, and a better understanding is urgently needed. Our study aimed to objectively determine the prevalence of, and factors associated with, SDB in a large sample in Benin, west Africa.

METHODS

In the Benin Society and Sleep (BeSAS) cross-sectional study, participants aged 25 years and older were recruited from both urban and rural areas. Rural participants were recruited from Tanve, a village located 200 km north of Cotonou, and urban participants were recruited from Cotonou. The participants underwent respiratory polygraphy at home using a type-3 device that measures airflow through a nasal pressure sensor, respiratory effort (thoracic movement), and pulse oximetry. Clinical and morphometric data were also collected. SDB severity categories were defined according to the apnoea-hypopnoea index (AHI), with mild-to-severe SDB (AHI ≥5/h), moderate-to-severe SDB (AHI ≥15/h), and severe SDB (AHI ≥30/h).

FINDINGS

The study was completed from April 4, 2018 to Jan 15, 2021. Of 2909 participants recruited in the BeSAS study, 2168 (74·5%) underwent respiratory polygraphy. For the 1810 participants with complete polygraphic data (mean age 46 years, SD 15; 1163 [64·2%] women), the prevalence of mild-to-severe SDB (AHI ≥5/h) was 43·2% (95% CI 40·9-45·5), of moderate-to-severe SDB (AHI ≥15/h) was 11·6% (10·2-13·1), and of severe SDB (AHI ≥30/h) was 2·7% (2·0-3·5). Factors independently associated with SDB were advanced age, male sex, large neck circumference, abdominal obesity, overweight or obesity, and snoring. After multivariable adjustment, severe SDB was independently associated with hypertension in women (odds ratio 3·99, 95% CI 1·04-15·33; p_trend=0·044), but not in men (odds ratio 0·67, 0·22-2·05; P_trend=0·63).

INTERPRETATION

The BeSAS study provides the first large-scale objective evaluation of SDB prevalence and associated factors in Africa. The high prevalence of SDB identified should stimulate the development of public health policies to prevent and treat this condition in African countries.

FUNDING

Ligue Pulmonaire Vaudoise, Switzerland.

Inter-arm difference in systolic blood pressure: Prevalence and associated factors in an African population

Objectives

Inter-arm blood pressure difference (IABPD) can lead to underdiagnosis and poor management of hypertension, when not recognized and are associated with increased cardiovascular mortality and morbidity. However, the prevalence and associated risk factors of IABPD in sub-Saharan Africa are unknown. This study aims to determine the prevalence and associated risk factors of IABPD among Tanve Health Study (TAHES) participants, a cohort about cardiovascular diseases in a rural area in Benin.

Methods

The cohort was conducted since 2015 among adults aged 25 years and over in Tanve village. Data were collected from February to March, 2020. Brachial blood pressure were recorded at rest on both arm with an electronic device. Systolic IABPD (sIABPD) was defined as the absolute value of the difference in systolic blood pressure between left and right arms ≥ 10 mmHg. A multivariate logistic regression models identified factors associated with sIABPD.

Results

A total of 1,505 participants (women 59%) were included. The mean age was 45.08 ±15.65 years. The prevalence of sIABPD ≥ 10 mmHg was 19% (95%CI: 17–21). It was 19% (95%CI: 16–22) in men and 20% (95%CI: 17–22) in women. In final multivariable model, the probability of sIABPD ≥ 10 mmHg increased significantly with age (adjusted OR (aOR) = 1.1; 95%CI: 1.02–1.20 per 10-years), hypertension (aOR = 2.33; 95%CI: 1.77–3.07) and diabetes (aOR = 1.96; 95%CI: 1.09–3.53).

Conclusion

Almost quarter of sample have a sIABPD ≥ 10 mmHg, with an increased risk with older age and hypertension and diabetes.

Normal values of proximal aorta diameters in healthy Sub Saharan Africans: The TAHES study

OBJECTIVES

Reported ranges of normal values are mostly issued from studies performed with Caucasians. This study is a part of TAHES, a population-based prospective cohort study in Benin and aims to establish normal reference values for echocardiographic diameters of the proximal aorta in Africans.

METHODS

Transthoracic echocardiography (TTE) examinations were performed by four cardiologists following pre-defined protocols, and analyzed off-line by a single observer. Aortic root diameters were measured during diastole for sinuses of Vasalva (SV), sinotubular junction (STJ) and proximal ascending aorta (AA), and during systole for annulus. Upper limits were defined as the 95th percentiles.

RESULTS

We included 513 normotensive, non-diabetic, and cardiovascular disease-free individuals (206 men, 307 women, age 40 ± 14 years). The diameters of the proximal aorta were significantly greater in men. The inner-edge-to-inner-edge non-indexed upper values for the annulus, SV, STJ and AA were respectively 25, 34, 28.5, 32 mm in men and 22, 30, 26, 30 mm in women. The leading-edge-to-leading-edge upper values were respectively 38, 35, 36 for men and 34, 33, 32 mm for women. No significant differences between sexes were recorded for body surface area (BSA)-indexed diameters of the annulus, STJ and AA. BSA-indexed SV dimension was greater in men than women were. SV, STJ, AA indexed-diameters correlated with age in both sexes but not for annulus indexed-diameter.

CONCLUSION

Normal values from a general population in West Africa could to differ from those established in Caucasian populations. Ethnic-specific reference diameters are here proposed for appropriate diagnosis of proximal aortic diseases in sub-Saharan Africa.

[Social representations of cardiovascular disease in the Tanvè Health Study (TAHES) cohort in Benin]

OBJECTIVE

To describe the social representations associated with cardiovascular diseases (CVD) in the village of Tanvè in Benin.

METHODS

Focus groups discussions and semi-structured interviews were conducted among participants of Tanvè Health Study (TAHES) cohort. Audio recordings were made during the interviews, as well as some note-taking. Data were organized by themes and analyzed to identify key representations that underlie attitudes and health care practices.

RESULTS

A total of 19 subjects (including 11 women) participated in 2 focus groups and 17 (including 5 women) in individual interviews. Etymologies of CVD's names evoke either clinical signs (example: ''tesisi glô mɛ'' [can't stand up]), guessed etiology (example: ''kuvitɔ zɔn'' [ghosts' disease]) or a local adaptation of a biomedical name (example: ''a'tension'' [from hypertension]), to cite the example of stroke. According to beliefs about etiology, diseases were classed as ''simple'' or "organic" diseases ("azɔn yaya") and ''supernatural'' or ''induced'' diseases linked to "azé" [immaterial witchcraft] or "bô" [material bewitchment]. Chronic or recurrent diseases usually end up in the ''supranatural'' category and induce the consultation of "bokɔnɔ᷉" (diviner) or other religious for diagnosis. Health care seeking refer to modern medicine, "amanɔn" (leaf-based care), "bokɔnɔ᷉" or traditional religious (various rites) and Christians (prayers).

CONCLUSION

Social representations of CVD in this community are based on ancestral beliefs, but are also influenced by modern knowledge. Taking them into account could improve quality of health to fulfill communities' care needs.

The prevalence, awareness, management and control of hypertension in men and women in Benin, West Africa: the TAHES study

BACKGROUND

Due to epidemiological transitions, Sub-Saharan Africa is facing a growing burden of non-communicable diseases, including cardiovascular diseases (CVDs). Among their risk factors, hypertension is a major determinant of CVDs, but the prevalence and level of awareness and management of this condition are poorly studied in African populations. The aim of this study was to determine the prevalence of hypertension and identify its associated risk factors as well as the awareness and management of this condition in a community-dwelling cohort in Benin.

METHODS

A cross-sectional door-to-door study was conducted in the population over the age of 25 years in Tanve, a rural setting in Benin. The questionnaire and anthropometric measurements of the World Health Organization STEPWISE survey were used. Blood pressure was measured using standard procedures.

RESULTS

The sample included 1777 subjects (60.9% females, mean age was 42.5 ± 16.5 years). The prevalence of hypertension was 32.9%, similar in men (32.8%) and women (33.0%, p = 0.9342). Age and obesity were significantly associated with hypertension. Less than half (42%) of hypertensive people were aware about their condition and only 46.3% of them were treated. Awareness ratios differed between men and women (respectively 32.9% vs. 47.5%; p = 0.0039) and was not influenced by age, education, occupation, marital status or income. Female sex was the only factor associated with better controlled HTN, independent of socio-economic parameters.

CONCLUSION

This large population-based study confirms the high prevalence, low awareness, and low control of hypertension in men and women in sub-Saharan Africa. Only half of the populations with hypertension are aware of their hypertension, indicating a high burden of undiagnosed and un-controlled high blood pressure in these populations.

Epidemiology of lower extremity artery disease in a rural setting in Benin, West Africa: The TAHES study

BACKGROUND

Data on epidemiology of lower extremity artery disease (LEAD) in general population in Sub-Saharan Africa are sparse. This study aims to estimate the prevalence of LEAD among participants of Tanve Health Study (TAHES), a cohort about cardiovascular diseases (CVD) in a rural setting in Benin.

METHODS

The cohort was launched since 2015 among adults aged over 25 years in Tanve, a village in Benin. Ankle-brachial index (ABI) was measured for the first time during the third annual visit of the cohort in 2017. Risk factors data were collected using the WHO STEPS adapted questionnaire in a systematic door-to-door survey. The LEAD was defined as ABI ≤ 0.90.

RESULTS

We recorded ABI among 1003 out of 1407 TAHES' participants. A predominance of females (61.4%) was observed. The mean age was 44.4 ± 15.7 years and 49.9% were under 40 years. Regarding CVD risk factors, prevalences were estimated for sedentary behavior (68.2%), harmful use of alcohol (3.9%), fruit and vegetable low intake (96.0%), tobacco smoking (5.2%), Overweight or obesity (Body mass index > 25) (27.7%), raised blood pressure (36.8%) and raised blood glucose (5.4%). Prevalence of LEAD was 5.5% (95%CI: 4.2%–7.1%) in the sample, 7.0% (95%CI: 5.1%–9.4%) in women and 3.1% (95%CI: 1.7%–5.5%) in men. Five individuals (0.5%; 95%CI: 0.2%–1.2%) had incompressible arteries (ABI ≥ 1.40), including four men. In multivariate analysis, LEAD was significantly associated with age ≥ 55 years (OR: 2.17; 95%CI: 1.20–3.92; p = 0.009) and female gender (OR: 2.27; 95%CI: 1.17–4.40; p = 0.014).

CONCLUSION

Prevalence of LEAD is high in rural Benin and predominates among women and people over 55 years old.