Background: Long regarded as Western diseases, diabetes and hypertension are becoming a serious threat to public health in developing countries and particularly in Sub-Saharan Africa [SSA]. However, there is few or no door-to-door study of cardiovascular disease [CVD] in SSA rural areas and particularly in Senegalese areas. Our aim was to determine the rate of CVD risk factors such as high blood pressure, diabetes and obesity in rural Senegal and study mechanisms of occurrence of these cardio-vascular complications.
Methods: Our study population included 207 adults, from the general population of a rural area in Ferlo located in the north-east of Senegal [Widou Thiengoli]. They were divided in four groups classified by age: 20 to 34 years [G1], 35 to 49 years [G2], 50 to 64 years [G3] over 65 years [G4]. Anthropometrics, biochemical and cardiovascular parameters were conducted in our study population.
Results: Comparison of the data for hypertension, diabetes and sedentary between different groups showed that the arterial hypertension increased significantly with age [27.2%, 36.7%, 65.9% and 84.8% in G1, G2, G3 and G4 respectively]. Diabetes or glycaemia was significantly [p<0.05] frequent in G3 followed by G2 compared to others groups. Sedentary behaviour increased proportionally with age and a significant difference [p<0.05] was found for all comparison between groups.
Conclusion: Our study demonstrated that the arterial hypertension phenomenon could be a real health problem in sub-Saharan Africa rural areas particularly in elderly population and these phenomena are related to advanced age through sedentary.

Chronic Non-Communicable Diseases [NCDs] represent a significant public health problem worldwide. They are the leading causes of death in both developed and underdeveloped countries. Cardiovascular diseases such as arterial hypertension type 2 diabetes and related risk factors such as obesity are implicated in the increase of mortality rate related to the NCDs [1]. Long regarded as Western diseases, diabetes and elevated blood pressure are becoming a serious threat to public health in developing countries and particularly in Sub-Saharan Africa [2-4]. According to World Health Organization [WHO], rates of type 2 diabetes and hypertension prevalence have been increasing in African continent generally and particularly in West Africa [2,5,6]. Opie, et al. reported in Sub-Saharan Africa [SSA] that about 80 million adults had high blood pressure in 2000 and recent epidemiological studies suggest that the proportions of people with hypertension would increase to 150 million by 2025 [5]. In several African countries, obesity and chronic cardiovascular disease [CVD] frequencies have reached epidemic proportions in adults. Cardiovascular diseases such as arterial hypertension or diabetes are also an economic problem, especially in sub-Saharan countries. Indeed, the total cost of cardiovascular diseases in few European countries might exceed 117.66 billion US dollars in 2014, and this cost could reach 1442.51 billion US dollars by 2020 [7]. In SSA, it is still difficult to estimate the cost of CVD but some values have been reported in some countries such as Senegal where the direct cost of stroke management was valued at 58500.94 US dollars with an average cost of 140.67 US dollars per patient [8].

Urbanization and socio-economic development are commonly cited as major factors related to increasing CVD and related risk factors [9-13]. In SSA, high blood pressure accounts for 9.4 million deaths, and this mortality is higher than that of other cardiovascular risks like chronic hyperglycemia, or dyslipidemia [14]. Hypertension associated with unhealthy diets and lack of physical activity, could have a multiplicative negative effects on cardiovascular health [15]. Recent data [2017] reported diabetes caused an additional 1.3 million deaths [16]. Recently studies demonstrated that overweight and obesity are linked to more deaths than underweight in African continent [17,18].
Moreover, studies have recently shown a relationship between the risk of developing CVD and high socio-economic level in developing countries, contrary to what is observed in developed countries where diabetes and high blood pressure are rather associated with low socio-economic status [19]. While CVD is less prevalent in rural versus urban areas in SSA, factors such as diabetes, high blood pressure and obesity are increasing in rural areas. Thus, we carried out this study to determine the rate of CVD risk factors, namely, high blood pressure, diabetes and obesity to study mechanisms of occurrence of these cardiovascular complications among in rural Senegal [West Africa].

Our study protocol was designed at the Laboratory of Physiology and Functional Explorations of the Faculty of Medicine, Pharmacy, and Odontology at the University Cheikh Anta Diop of Dakar [UCAD] in accordance with the guidelines set by the Declaration of Helsinki and was approved by the Ethics Committee of UCAD. Descriptive and transversal study was conducted by staff of Physiology Laboratory in collaboration with Unite Mixte Internationale [UMI] 3189-Environnement-Sante-Societe, CNRSUCAD during the period from March 2015 to October 2016 in rural area, 380 km from Dakar Senegal, West Africa.

Our study population included 207 adults; 105 women and 72 men; and was from the general population of a rural area in Ferlo which is an area located in the north-east of Senegal [Widou Thiengoli]. Study sample was randomized and our subjects were from ethnic Peulh who practiced mainly livestock and storm agriculture and live regularly on livestock and agricultural products [milk, meat, cereals, etc.]. There is no electricity, water supply [use drilling water] or shopping center or point of sale of refined food products in Widou Thiengoli. Participants were informed of the procedures and purposes of the study and gave written informed consent to participate to the present study and measurements were conducted in rural area.
Surveys concerning the socio-demographic characteristics of our study population were carried out using anonymous questionnaires before performing anthropometric, cardiovascular and biochemical measurements.

A full clinical examination was employed to measure anthropometric [age, height, and body weight] parameters. Cardiovascular parameters such as systolic and diastolic arterial pressures [SAP and DAP, respectivel] were evaluated in our subjects. SAP and DAP were manually measured three times in the left arm using a manual sphygmomanometer [Omron M3, Intellisense, Japan], in standardized sitting position and after 30 min of rest [20]. Mean arterial pressure [MAP] was evaluated by MAP = [SAP + 2DAP]/3, and body mass index [BMI] of the subjects was calculated using Quetelet equation, BMI [kg /m2] = weight [kg ] / [height [m ]]2.
For Lipid profile and glycaemia, blood samples were withdrawn and glucose and lipid levels were evaluated using enzymatic method [OneTouch Select; for glycemia] and Lipid ProTM for total cholesterol, HDL cholesterol and triglycerides.
LDL- cholesterol was calculated according to the Friedewald formula: LDL-cholesterol = Cholesterol Total - [HDL cholesterol + Triglycerides /5] and the ratios of total cholesterol/HDLcholesterol and LDL/HDL were evaluated.
All measurements [anthropometrics, biochemical and cardiovascular parameters] were performed after eight hours of fasting in the morning of the day where all clinical measures were first taken [i.e., 8:00 h]. Data were processed at the Laboratory of Physiology and Functional Explorations of the Faculty of Medicine, Pharmacy and Odontology at the University Cheikh Anta Diop of Dakar [UCAD].

To assess the relationship between age range and our outcomes of interest in the Senegalese rural population, Chi-square tests were employed. Also, data were expressed as mean +/- standard deviation, percentages, and relative values. Our study population was divided into four age groups according to methodology of a study made on hypertension in Ferlo [21]: 20 to 34 years for group [G1], the subjects aged 35 to 49 years constituted group 2 [G2], group 3 [G3] was composed of subjects aged 50 to 64 years and subjects aged over 65 years were in group 4 [G4]. For the comparison of frequencies of arterial hypertension [defined by the standards of the American Heart Association i.e. systolic blood pressure [SBP] ≥ 140 mmHg and / or diastolic blood pressure [DBP] ≥ 90 mm Hg [22] and diabetes [according to WHO criteria in 2006 [fasting blood glucose ≥ 7.0 mmol/L] [23] between the different groups, we used the same statistical test [Ch-2 test ]. For cardiovascular and metabolic variables, we calculated the Odds Ratio [OR] with 95% confidence interval [95%IC] to evaluate the risk of occurrence of these complications in each group. Cardiovascular [SAP, DAP and MAP] biochemical [plasma glucose and profile lipid] parameters and BMI were compared between the four groups using a oneway ANOVA with Newman- Keuls for multiple comparisons. We also used a Pearson test for correlations between age and cardiovascular and metabolic parameters such as mean arterial pressure [MAP] and glycaemia.

Our study was carried out on 207 subjects, the extreme ages were 20 and 92 years, and the population comprised 34.8% of men and 65.2% of women with a sex ratio of 0.53. The population was predominantly from the ethnic Peul [98.1%]. The main occupations encountered were housewives [50.7% among our study population] composed only of women, then livestock [28%] practiced mainly by men. Trade was practiced at 3.9% and agriculture was practiced by 1.4% of the population. The proportion of unemployed persons was 15.9% and they were elderly and /or disabled.

Among our study population, 6.3% were educated [6% of men and 7% of women], but they did not go further than elementary school. The proportion of married couples was 84.1%. Young subjects [from 20 years to 34 years] represented 39.1% of the study population, and adults were 44.9%; 23.6% of whom are aged between 35-49 years and 21.3% for those aged 50 to 64 years. The elderly occupied 15.9% of our study population.
Women were more numerous in the different groups. The sex ratio [male/female] was 0.65, 0.4, 0.69, and 0.83 in young, adults groups and in elderly population respectively (Table 1). Cardiovascular and biochemical parameters and BMI in different groups Arterial pressures [systolic, diastolic and mea] were significantly [p<0.05] elevated in the groups of older subjects [G3 and G4] compared to others [G2 and G1] while comparison of BMI showed a significant [p<0.05] difference between G3 and G4 [22 + 5.46 kg/m2 and 18.5 + 6.77 kg/m2 respectively]. The global prevalence of high blood pressure was 46.6%. For biochemical parameters [glycemia and lipid profile] no significant difference was found between groups (Table 2).

Comparison of the hypertension, diabetes and sedentary prevalence between different groups showed that the arterial hypertension increased significantly with age [percentage of hypertensive subjects was 27.2%, 36.7%, 65.9% and 84.8% in G1, G2, G3 and G4 respectively]. On the other hand, mean arterial pressure was significantly correlated with age [p=0.002; r = 0.34]. Nevertheless, diabetes or high glycaemia was significantly [p<0.05] frequent in G3 followed by G2 compared to others groups [(G1 vs G2: p<0.05, OR [95% CI]: 0.04 [0.002 -0.74]; [G1 vs G3: p<0.05, OR [95% CI] 0.03 [0.001- 0.55]]; G3 vs G4 [(p<0.05  OR [95% CI]: 3.58 [1.12-11.42]]. For sedentary data, we observed that sedentary behavior increased proportionally with age and a significant [p<0.05] difference was found for all comparison between the groups (Table 3).
In group 1, all sedentary subjects were men [p <0.05, Odds ratio [95% IC]: 40.02 [2.2-71.7], however in group 3 women were significantly more sedentary than men [p <0.05, Odds ratio [95% IC]: 0.17 [0.05-0.7]. Comparison of other cardiovascular risks [diabetes and high arterial pressure] there were no significant difference between women and men (Table 4).

Our study showed that more than half of the population was under 40 years old and that people over 50 accounted for 21.25%. Women were more numerous than men and they had very little schooling level. We found that systolic, diastolic and mean arterial pressures were significantly higher [p <0.05] in elderly people [over 50 years of age [G3-G4] than adults or young. Our results demonstrated also that arterial hypertension proportion was increased significantly in G3 and G4 with 65.9% and 84.8% respectively compared to others groups. Positive correlation [p = 0.002, r = 0.34] between age and MAP was reported in our study population. These results could prove that arterial hypertension is a public health problem in Senegalese rural population, particularly in elderly people such as those in Widou Thiengoly. It has been well reported in some studies that the prevalence of hypertension increases with age [21,24-27]. For example surveys showed in Sub Saharan African rural areas that the prevalence of arterial hypertension is about 30-40% in population aged over 65 years [11,28-30]. However, our study, is the first which evaluate the links of arterial hypertension, age and sedentary and we hypothesize that arterial hypertension could occur in old population living in rural area through sedentary. In our study, no significant difference was observed between elderly subjects group and the others groups for the cardiovascular risks such as glycaemia or lipid profile. Furthermore, BMI was significantly higher in adults groups compared to elderly group whereas; no subject in our study population was obese. According to studies obesity is considered one of the main risk factors for high blood pressure and diabetes [1,4,17,31-34]. Indeed, recently [2016] Diaw, et al. found a strong correlation between BMI, blood glucose level and blood pressure in adult population living in urban areas [35]. The absence of obesity in Senegalese rural population especially adults could be explained by their lifestyle.

In fact their professional activities [breeder and/or agriculture for men and household for women] and low-fat diet could be a protective factor against overweight and obesity [10,36,37]. Although, the elderly were sedentary and had no professional activities, they were less overweight and more hypertensive than adults. This could highlight the relationship between arterial hypertension and sedentary lifestyle in older subjects compared to adults regardless of sex [hypertension: 65.9% in G3 and 84.8% in G4; p <0.05; IC95% OR: 0.34 [0.17 - 0.68] and sedentary 45.5% in G3 and 75.8% in G4 p <0.05 IC95% OR: 0.26 [0.14 -0.49]. According to the literature, increasing physical activity and reducing sedentary behaviors are part of non-medicinal means of preventing cardiovascular complications such as arterial hypertension or diabetes [38-46]. In our study it seems that women are more active than men. But our old population did not engage in physical activities and their professional and domestic activities decrease with age because they are replaced in these spots by the younger ones and this phenomenon could be explained by sociocultural factors.

Nevertheless, our study has some limitations. First, our sample is cross sectional and randomized so that cannot deduce causality between sedentary and arterial hypertension. Second our biological measurements could not be performed by the methods usually described as reference methods in biomedical research because of the rural context [very remote site of cities, lack of electricity or conservation methods of biological samples]. Thirdly renal functions have not been explored in this work. In conclusion, our study demonstrated that the arterial hypertension phenomenon could be a real health problem in sub-Saharan Africa rural areas particularly in elderly population and these phenomena are related to advanced age through sedentary. Future researches should be necessary to 1] explore the Renin-Angiotensin-Aldosterone and nerve systems which are an important system for regulating blood pressure and 2] to focus on physical activity related strategies to reduce the sedentary phenomena in elderly rural population.

This work was cofunded by the Labex DRIIHM, French programme "Investissements d'Avenir" [ANR-11-LABX-0010] which is managed by the ANR. The authors would like to thank all the participants of study as well as Mr Jean-Luc Peiry, Director of the International Research Unit 3189 CNRS-UCAD and Karine Ginoux, Administrative Director and Program Coordinator UMI 3189 CNRS-UCAD.

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