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Journal of Hypertension:
doi: 10.1097/HJH.0b013e32835a6611
ORIGINAL PAPERS: Epidemiology

Epidemiological Trial of Hypertension in North Africa (ETHNA): an international multicentre study in Algeria, Morocco and Tunisia

Nejjari, Chakiba; Arharbi, Mohammedb; Chentir, Mohand-Tayebc; Boujnah, Rachidd; Kemmou, Omare; Megdiche, Hafedhf; Boulahrouf, Fadhilag; Messoussi, Karimag; Nazek, Lailae; Bulatov, Vladimire

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aLaboratoire d’épidémiologie et de Recherche Clinique, Faculté de Médecine et de Pharmacie, Fès

bCHU Avicenne, Rabat, Morocco

cUniversity Hospital Mustapha, Algiers, Algeria

dCHU Mongi Slim La Soukra, Tunis, Tunisia

eNovartis Pharma Maroc SA, Casablanca, Morocco

fNovartis Pharma Services AG, Representative Office Tunis, Tunis, Tunisia

gNovartis Pharma Services AG, Bureau de Liaison Algérie, Algiers, Algeria

Correspondence to Dr Omar Kemmou, Novartis Pharma Maroc SA, B.P. 7545, 20003 Casablanca, Morocco. Tel: +212 522 349 290; fax: +212 522 359311; e-mail: omar.kemmou@novartis.com

Abbreviations: CRF, case report form; ESC, European Society of Cardiology; ESH, European Society of Hypertension; ETHNA, Epidemiological Trial of Hypertension in North Africa; HRT, hormone replacement therapy

Received 7 February, 2012

Revised 1 August, 2012

Accepted 13 September, 2012

The work was presented as an oral presentation at the 21st European Meeting on Hypertension and Cardiovascular Prevention, 17–20 June 2011, Milan, Italy.

Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal's Website (http://www.jhypertension.com).

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Abstract

Objectives: Inhabitants of developing countries such as those in North Africa have experienced lifestyle changes that have increased the risk of cardiovascular disease. The aim of the Epidemiological Trial of Hypertension in North Africa (ETHNA) was to evaluate the prevalence and clinical profile of hypertension in a large sample of individuals in North Africa.

Methods: This was an international, multicentre, epidemiological, cross-sectional study conducted in patients consulting primary care physicians in Algeria, Tunisia and Morocco. Data were collected via a medical examination and questionnaire covering patient demographics, medical history and cardiovascular risk factors. Associations between hypertension and patient characteristics were determined using conventional parametric statistical tests.

Results: In total, 28 500 individuals attending primary care physicians participated in this study: 41.8% from Algeria, 37.6% from Morocco and 20.6% from Tunisia. Mean age was 49.2 ± 16.8 years. The total prevalence of hypertension was 45.4% [95% confidence interval (CI) 44.8–46.0]; 29.0% of patients with hypertension were newly detected at the study visit. When adjusted for age and sex, the overall prevalence of hypertension was 26.9% (95% CI 26.4–27.4). Overall, 88.0% of the patients with hypertension were receiving or were newly prescribed antihypertensives (history of hypertension, 91.2%; newly detected, 80.3%). Among patients with a history of hypertension receiving antihypertensives at the study visit, only 35.7% had controlled hypertension.

Conclusion: This study suggests that the prevalence of hypertension in North Africa is high. Hypertension may also be underdiagnosed and ineffectively treated. Greater awareness and improved management of hypertension and cardiovascular risks are needed in this region.

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INTRODUCTION

Hypertension is very common in industrialized countries and is an important global healthcare problem. Analysis of data from several national surveys in a 2003 report indicated that the prevalence of hypertension is 28% in North America and 44% in Europe [1]. It is predicted that the global prevalence of hypertension could be around 30% by 2025 [2]. Hypertension is associated with an increased risk of comorbidities such as diabetes, kidney disease and cardiovascular events (e.g. myocardial infarction, stroke and death). As cardiovascular disease is a leading cause of death worldwide, at-risk patients need to be identified so that their disease can be treated and controlled.

In many developing countries that have undergone rapid urbanization, economic growth and technological advances, lifestyles have changed, becoming similar to those of Western countries [3]. These lifestyle changes include dietary modifications as a consequence of alterations to food supplies, and reductions in physical activity, both in the workplace and at leisure [4]. The result has been an increase in the prevalence of cardiovascular risk factors including hypertension, raising concerns about the potential development of an epidemic of cardiovascular disease in developing countries [5].

One region that has seen considerable economic development over the past few decades is North Africa (Morocco, Algeria, Tunisia, Libya and Mauritania). However, a good understanding of the current levels of hypertension and cardiovascular disease risks in the region is lacking. Some data from studies on the prevalence of hypertension in specific countries within the region are available. Data collected from 957 individuals in 1995–1996 in the city of Sousse, Tunisia, estimated the prevalence of hypertension to be 28.9% [6], while a 2004–2005 study in over 8000 adults (aged 35–70 years) from across Tunisia reported a prevalence of 30.6% [7]. The study by Tazi et al. in the year 2000 [8] in 1802 individuals revealed the prevalence of hypertension was 33.6% in Morocco. Two studies in Algeria, one in the city of Tlemcen in 805 participants [9] and another in the Algerian Sahara in 1346 participants [10], reported hypertension prevalence of 33 and 44%, respectively. Most of the above studies were limited to fairly small sample sizes (<2000 participants) and the populations sampled may not be representative of the respective countries as a whole. Obtaining up-to-date information from a much larger sample of the population may help to clarify the prevalence of hypertension in this region.

In this article, data from the Epidemiological Trial of Hypertension in North Africa (ETHNA) are presented. The aim of ETHNA was to evaluate the prevalence and clinical profile (stage, treatments, complications and risk factors) of hypertension in a large sample of individuals visiting primary care physicians in a cross-section of countries in North Africa.

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METHODS

Location and participants

This was an international, multicentre, epidemiological, cross-sectional study conducted in patients attending primary care physicians in three countries (Algeria, Tunisia and Morocco) in North Africa between September 2008 and January 2009. Eligible patients were aged 18 years or older (20 years or older in Tunisia) of either sex who were willing to participate in the survey. Patients who had fever (≥38°C) were excluded from the study. The study was reviewed by the Independent Ethics Committee of each country and was conducted according to the ethical principles of the Declaration of Helsinki. Informed consent was obtained from all participants.

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Data collection and medical examination

Data were collected by participating primary care physicians using a standardized questionnaire that covered demographics of the patient, personal and family medical history, risk factors for cardiovascular disease and hypertension (including stress and insomnia), and whether a blood pressure (BP) measurement had been recorded in the last year. If the patient had a history of hypertension, additional information from their medical history was collected including duration of hypertension, prescription of antihypertensive medication [including type(s), number of medications, any single-pill combinations] and history of hypertension-related complications (including left ventricular hypertrophy, angina, myocardial infarction, chronic heart failure, stroke, chronic kidney disease, retinopathy, revascularization or peripheral arterial disease).

Patients were also clinically examined and measurements were taken for weight, height, waist circumference and BP. Two BP measurements were planned: one after 5 min of rest and the second following a further 2-min rest after the completion of the first measurement. When possible, BP measurements were recorded as the mean of the two measurements. Hypertension was identified according to the criteria of the European Society of Hypertension and the European Society of Cardiology (ESH/ESC) guidelines [11]: grade 1 hypertension, SBP 140–159 mmHg and/or DBP 90–99 mmHg; grade 2 hypertension, SBP 160–179 mmHg and/or DBP 100–109 mmHg; grade 3 hypertension, SBP ≥180 mmHg and/or DBP ≥110 mmHg; systolic hypertension (also known as isolated systolic hypertension) was graded (1, 2 or 3) according to the SBP values in the above ranges, provided that DBP was <90 mmHg.

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Data quality assurance

Questionnaire results were collected by study investigators on Novartis case report forms (CRFs) printed on paper. The CRFs were forwarded to the Novartis medical document reception centre where they were checked for completeness. Data from the CRFs were entered into a study database by a third party (Laboratoire d’Epidémiologie et de Recherche Clinique, Faculté de Médecine et de Pharmacie, Fès, Morocco) using double data entry with verification upon second entry. The entered data were checked and obvious errors were corrected. No data clarifications were sent to investigators. The database was locked after it had been declared complete and accurate. After this point, data errors could be corrected only by joint written agreement of all involved parties. The data were managed using SPSS software (version 17.0; IBM Corporation, Armonk, New York, USA).

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Statistical methods

Initially, descriptive analyses were used to determine the crude prevalence of hypertension over the whole sample. In addition, age-adjusted and sex-adjusted rates were calculated by multiplying the age-specific and sex-specific rate for each age group in the study population by the appropriate weights from a standard population. The overall age-adjusted and sex-adjusted rates were the sum of these products. The standard population was calculated as the sum of the populations from the participating countries (Algeria, Morocco and Tunisia) using world population data from 2010 [12].

The associations between various facets of hypertension (e.g. a history of hypertension, newly detected hypertension, hypertension severity, controlled hypertension) and patient demographics and personal medical profile (e.g. age, sex, personal and family medical history, BMI, smoking and current treatment) were investigated. Statistical analyses were based on conventional parametric tests (χ2-test, Student's t-test and analysis of variance). A test was considered significant when P < 0.05. Where comparisons are made within a category containing more than two subcategories, P values have been denoted ‘within category’.

The sample size was calculated based on an estimated prevalence of hypertension of 30%. With a risk of error of 0.01 (1%), a difference of imprecision of 1.0% and a cluster effect of 2, the number to be included in the study was estimated at 27 488 participants. To compensate for invalid data, this figure was rounded up to 30 000 participants: 12 000 for Morocco, 12 000 for Algeria and 6000 for Tunisia. Statistical analyses were performed using SPSS (version 17.0).

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RESULTS

Participants

From the 30 000 planned participants, 28 500 were enrolled across the participating centres: 11 905 individuals (41.8%) were recruited from Algeria, 10 714 (37.6%) from Morocco and 5881 (20.6%) from Tunisia.

The characteristics of the study population are presented in Tables 1 and 2. The mean age of participants was 49.2 ± 16.8 years, with almost 30% of participants older than 60 years of age. More than 60% of the participants were women and over two-thirds of the participants lived in urban areas. Almost 40% of participants were illiterate and 13% were educated to university graduate level. The mean BMI of the participants was 26.4 ± 5.2 kg/m2. Around 42% of the participants had a normal BMI, with almost 56% of participants either overweight or obese according to the World Health Organization classification. Almost 40% of the participants had a family history of cardiovascular disease and over half of the participants had a family history of hypertension. Around three-quarters of the participants reported having at least one BP measurement in the past 12 months.

Table 1
Table 1
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Table 2
Table 2
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Prevalence of hypertension

At the study visit, two BP measurements were recorded for 98.2% of the participants. Among the 28 500 participants surveyed, 12 933 individuals had hypertension, an overall crude prevalence of 45.4% [95% confidence interval (CI) 44.8–46.0]. Of these individuals, 9186 (71.0%) had a history of hypertension and 3747 (29.0%) were detected with hypertension at the time of the study assessment. When adjusted for age and sex, the overall prevalence of hypertension was 26.9% [95% CI 26.4–27.4; 25.4% in men (95% CI 24.6–26.2) and 28.4% in women (95% CI 27.7–29.1)]. The duration of hypertension in patients with a history of hypertension averaged 8.3 ± 6.7 years. In more than half of the patients (52.7%), the duration of hypertension was more than 5 years.

An overview of hypertension severity in patients with a history of hypertension is shown in Fig. 1a. In total, fewer than 18% of patients had either normal or optimal BP at the time of the study visit. Around 18% of the patients had normal–high BP and around 20% of the patients had isolated systolic hypertension grade 1. Of patients who were untreated, approximately 20 and 15% had hypertension grade 2 and grade 3, respectively.

Figure 1
Figure 1
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An overview of the severity of hypertension in patients with newly detected hypertension is provided in Fig. 1b. Approximately 40% of these patients had hypertension grade 1 or grade 2 (around 20% each). Almost 40% of newly detected patients had isolated systolic hypertension grade 1.

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Characteristics of patients with a history of hypertension

The proportions of patients with a history of hypertension according to their socio-demographic characteristics are summarized in Table 3. The proportions of patients with hypertension increased with age (P < 0.00001); 63.2% of the participants aged 60 years or older had a history of hypertension, compared with just 1.8% of those aged 18 to less than 30 years. Hypertension was more common in rural than in urban areas (34.9 vs. 32.5%; P = 0.0001), in illiterate participants than in those with some formal education (e.g. 47.5% for illiterate vs. 17.0% for university graduates; P < 0.00001 within category) and in women than in men (34.9 vs. 29.9%; P < 0.00001).

Table 3
Table 3
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The proportions of patients with a history of hypertension (out of the total study population) according to their personal medical profiles are provided in Table 4. Hypertension was more common in ex-smokers than in nonsmokers (45.3 vs. 32.8%; P < 0.00001 within category). In addition, hypertension was more common in individuals who had abdominal obesity, diabetes, hypercholesterolemia and kidney failure than in individuals without these comorbidities (all P < 0.00001). Hypertension was also more common in individuals who were overweight or obese than in those who were of normal weight or underweight (P < 0.00001 within category).

Table 4
Table 4
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Figure 2 shows hypertension-related complications experienced by patients with a history of hypertension. Overall, primary care physicians reported that almost 64% of the patients had not experienced any complications (data not shown). The most commonly reported complication was left ventricular hypertrophy, which was experienced by almost 20% of patients. Both angina and retinopathy were experienced by approximately 10% of the patients. Complications of hypertension were more common in patients who had had hypertension for more than 5 years.

Figure 2
Figure 2
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Treatment and hypertension control in patients with a history of hypertension

Among the 9186 patients with a history of hypertension, 8378 (91.2%) received antihypertensive medication. The interventions received by this group of patients are shown in Fig. 3a. Almost two-thirds of the patients were provided with lifestyle and dietary advice. About 45% of patients were prescribed diuretics and 35% of the patients were prescribed angiotensin-converting enzyme (ACE) inhibitors. Approximately 28% of the patients were prescribed angiotensin receptor blockers (ARBs) and 29% were prescribed calcium channel blockers (CCBs).

Figure 3
Figure 3
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The numbers of drugs prescribed to patients with a history of hypertension are shown in Fig. 3b. Almost 10% of the patients were not prescribed any medication. Around 45% of the patients were prescribed one medication and 32% of the patients were prescribed two medications. In patients receiving monotherapy, those who had optimal, normal or normal–high BP, or hypertension grade 1 tended to have lower rates of prescription of diuretics and higher rates of prescription of ARBs or ACE inhibitors (Supplemental Digital Content 1, http://links.lww.com/HJH/A203). Patients who had either hypertension grade 2 or 3 were more frequently prescribed diuretics than ARBs or ACE inhibitors. Of the 2951 patients receiving two medications, 973 (33.0%) were receiving single-pill combinations.

Overall, only 35.7% of patients with a history of hypertension had controlled hypertension (BP < 140/90 mmHg) at the time of the study visit. In all the groups of patients who received treatment with one, two or three medications, rates of controlled hypertension were approximately 37% (37.7, 37.2 and 36.9%, respectively). Of the patients receiving four medications, or five or more medications, 31.0 and 15.4%, respectively, had controlled hypertension. In the group of patients who were receiving no medication, 21.3% had controlled hypertension.

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Hypertension control according to patient characteristics

The proportions of patients with controlled hypertension (BP < 140/90 mmHg) according to their socio-demographic characteristics are shown in Table 5. Controlled hypertension was more common in younger than in older patients (P < 0.01), in female than in male patients (36.6 vs. 34.0%; P = 0.01) and in patients from urban areas than in those from rural areas (37.3 vs. 32.2%; P = 0.00001). Hypertension control was also higher in university graduates than in patients educated to lower levels (P < 0.00001 within category).

Table 5
Table 5
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The rates of hypertension control according to the medical profiles of patients are shown in Table 6. Controlled hypertension was less common in patients with abdominal obesity than in those without (33.7 vs. 38.6%; P < 0.00001). Similarly, patients with high cholesterol levels were less likely to have controlled hypertension than those with normal cholesterol levels (34.3 vs. 37.4%; P < 0.01). In addition, patients who were overweight or obese had lower hypertension control rates than those with normal or low BMI (P < 0.00001 within category). Controlled hypertension was more common in nonsmokers and ex-smokers than in current smokers (P < 0.0001 within category).

Table 6
Table 6
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Characteristics of patients with newly detected hypertension

Among 18 735 individuals without a history of hypertension, 3747 participants (20.0%) were detected with hypertension at the time of the study visit (representative of 29.0% of all patients with hypertension in the study). The proportions of patients with newly detected hypertension according to their socio-demographic characteristics are summarized in Table 7. The frequency of newly detected hypertension increased significantly with age (P < 0.00001). The proportion of individuals with newly detected hypertension was also higher in men than in women (21.4 vs. 19.2%; P < 0.001) and in people from rural areas than in those from urban areas (23.2 vs. 18.9%; P < 0.00001). Newly detected hypertension was also higher in illiterate people than in those with a formal education (P < 0.00001 within category).

Table 7
Table 7
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Table 8 shows the proportions of patients with newly detected hypertension according to medical profile. Newly detected hypertension was more common in diabetic than in nondiabetic patients (P < 0.00001), and in patients with high cholesterol than in those with normal cholesterol levels (36.0 vs. 18.3%; P < 0.00001). The prevalence of newly detected hypertension increased with BMI (P < 0.00001).

Table 8
Table 8
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Treatments prescribed to patients with newly detected hypertension

Among the 3747 patients with newly detected hypertension, 3007 (80.3%) received a prescription for antihypertensive medication [data were missing for 473 patients (12.6%)]. The types of interventions are shown in Fig. 4a. Dietary and lifestyle advice were provided to around 83% of the patients. Approximately 39% of the patients were prescribed ARBs and diuretics were prescribed to around 22% of patients. ACE inhibitors were prescribed to only 12% of the patients. The numbers of prescribed medications are shown in Fig. 4b. About 27% of patients in this group were prescribed no medication, 55% were prescribed one medication and 17% of them were prescribed two medications.

Figure 4
Figure 4
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DISCUSSION

The ETHNA study shows that the prevalence of hypertension is high in North Africa. Of the 28 500 individuals from participating countries (Algeria, Morocco and Tunisia), 45.4% had hypertension. Of these individuals, 71.0% had a history of hypertension, and 29.0% were newly detected with the condition and thus unaware of their hypertension status. After adjusting for age and sex, the overall prevalence of hypertension was 26.9%. The prevalence of both a history of hypertension and newly detected hypertension increased significantly with age. Hypertension was higher in illiterate individuals and those from rural areas than in those formally educated or from urban regions, respectively. Among patients with a history of hypertension, 91.2% received antihypertensive medication. The proportion of individuals with controlled hypertension was low (35.7%), although hypertension control was significantly higher in treated than in untreated patients.

This is the first integrated study consisting of pooled data from three different countries on the prevalence of hypertension in North Africa. The study benefits from a large sample size (28 500 participants) and thus helps to more clearly define the epidemiology of hypertension and other cardiovascular risk factors in adults in the region. The results from this study suggest that hypertension is underdiagnosed and undertreated in North Africa. Additionally, the overall age-adjusted and sex-adjusted prevalence of hypertension in the region (26.9%) is similar to that for North America (28%), but lower than that in Europe (44%) [1]. The age-adjusted and sex-adjusted prevalence of hypertension identified in our study is also similar to that described for Tunisia (30.6%) in a recent report of a 2004–2005 national survey [7].

In the overall ETHNA population, hypertension risk factors were common; around 41% of the participants had abdominal obesity, 22% had a BMI greater than 30  kg/m2 and 19% had high cholesterol levels. These trends can, at least in part, be attributed to the changes in lifestyle, especially diet, that have been occurring in developing countries over the past few decades [3–5]. It has been noted that in countries in the Middle East and North African region, daily calorie intake has increased by approximately 730 kcal per adult per day between 1970 and 2005 [3]. In addition, intake of saturated animal fats and refined carbohydrates has increased while intake of whole grain cereals, fruit and vegetables has decreased. Available information on the physical activity patterns of people living in the North African region is increasing. One Algerian study in the city of Tlemcen found that 43% of the population surveyed led a sedentary lifestyle [13]. A population-based survey in Morocco indicated that the prevalence of physical inactivity was 16.5%, and that high income and urbanization were the main determinants of physical inactivity [14]. General trends also suggest that the prevalence of physical inactivity is high in the Middle East and North Africa [3]. Infrastructural and environmental factors may contribute to these physical inactivity patterns. For example, outdoor activities in the region may be hampered by lack of public parks, walking tracks and bicycle paths, and the hot climate [3].

Other trends of interest in this study include associations between hypertension and socio-demographic characteristics. For example, there is a higher prevalence of hypertension in rural than in urban areas (34.9 vs. 32.5%, respectively, for patients with a history of hypertension, and 23.2 vs. 18.9% for newly detected patients). It is likely that the availability of healthcare resources is more limited in rural areas, which may account for these differences.

The study also revealed that a history of hypertension is more common in women than in men (34.9 vs. 29.9%). This could be related to the fact that around 50% of the women in the study were postmenopausal. The prevalence of hypertension was significantly higher in postmenopausal women than in younger women (58.4 vs. 12.5%). However, links between cardiovascular risk and postmenopausal status have been an area of debate [15]. It may be argued that any increase in the prevalence of hypertension in these women could be attributed to their age. The lower prevalence of hypertension in postmenopausal women receiving hormone replacement therapy (HRT) compared with women not receiving HRT seen in this study [45.0% (n = 202) vs. 59.9% (n = 6948)] should also be viewed with caution. The relationship between HRT and hypertension varies depending on the patient and the type of therapy used [15,16]. Given that the number of women receiving HRT in the study was low, this finding should be interpreted with care. The fact that a history of hypertension was more prevalent in women than in men in this study may be a consequence of women being more likely to consult a physician for a health problem in general (increasing the likelihood of detection of hypertension).

This study also revealed that the prevalence of isolated systolic hypertension grade 1 was higher than systolic/diastolic hypertension (all grades), especially in newly detected patients. This is possibly due to age, given that the average age of the entire study population was 49.2 ± 16.8 years. An underlying cause of isolated systolic hypertension is reduced elasticity and compliance of large arteries resulting from age. Studies show that in untreated patients over 50 years of age, isolated systolic hypertension is the predominant subtype of hypertension [17,18].

The results of ETHNA also indicate that patients with hypertension may not be receiving optimal treatment for achieving adequate BP control. Although 91.2% of patients with a history of hypertension were prescribed antihypertensive medication, only 35.7% of patients had controlled hypertension (BP < 140/90 mmHg). This BP control rate is, however, higher than that reported from a national survey in Tunisia, in which just 24.1% of treated patients with hypertension had controlled BP [7]. In high-risk patients (e.g. those with complications such as diabetes or kidney failure), guidelines suggest that BP goal should be set lower (<130/80 mmHg). Hence, rates of controlled hypertension in this study may actually need revising downwards, which may bring them into line with the Tunisian study.

Patients with poorly controlled hypertension are at increased risk of cardiovascular events. In recent years, there has been increased focus on the potential benefits of prompt BP lowering. For example, in the Valsartan Antihypertensive Long-term Use Evaluation (VALUE) study, patients who achieved BP response within 1 month of initiation of therapy had a significantly lower risk of cardiac events than those who achieved BP response after 1 month [19]. Similarly, the Systolic Hypertension in Europe (Syst-Eur) study revealed that early treatment of elderly patients was associated with fewer strokes and major cardiac events than delayed treatment [20]. Therefore, the importance of optimizing therapy, including appropriate follow-up to check for BP response, must be emphasized and may be an area for improvement in North Africa.

In the ETHNA study, 45% of patients with a history of hypertension were prescribed diuretics, 35% were prescribed ACE inhibitors, 29% were prescribed CCBs and 28% were prescribed ARBs. In contrast, patients with newly detected hypertension were mainly prescribed ARBs and diuretics, at different rates (39 and 22%, respectively) from patients with a history of hypertension. European treatment guidelines for hypertension [11,21] do not explicitly recommend particular medication types for initiating therapy. In contrast, US guidelines [22] recommend initiating therapy with diuretics in elderly patients with isolated systolic hypertension or in patients with uncomplicated hypertension. In patients at higher cardiovascular risk, or in those who have comorbidities such as diabetes or kidney disease, ACE inhibitors or ARBs should be considered, usually in combination with a diuretic. With this in mind, the prescribed medications for patients with a history of hypertension in ETHNA appear to fall within guidelines, at least in terms of the types of medications prescribed. One possible exception is the level of prescription of β-blockers (24%). β-Blockers are generally recommended as antihypertensive treatment following cardiac events such as myocardial infarction or heart failure, or for patients with comorbidities such as angina [11]. Although these complications were reported in the study in around 5–10% of patients, it is unclear whether these levels reflect the need for the rate of β-blocker prescription seen in ETHNA. Another point of concern relates to the types of medications prescribed to those receiving monotherapy, in that, individuals with more severe hypertension tended be prescribed diuretics more often than other medications such as ACE inhibitors or ARBs.

Although many patients with hypertension will benefit from treatment with a single agent in combination with lifestyle changes, US and European treatment guidelines indicate that therapy for patients with BP more than 20/10 mmHg above target should be initiated with two agents from different therapeutic classes [11,21,22]. Within the group of treated patients with a history of hypertension in ETHNA, patients were most likely to be receiving one medication, with considerably fewer patients receiving two (45 vs. 32%, respectively). Of patients receiving combination therapy with two medicines, 33% were prescribed a single-pill combination. In patients with newly detected hypertension, more than half (55%) of patients were prescribed one medication and only 17% were prescribed two. Given that a substantial proportion of patients were identified as having hypertension grade 2, it may be concluded that combination therapy is underprescribed in North Africa. This is supported by the fact that the rates of controlled hypertension were constant and low (∼37%) in all patients treated with one, two or three medications. It is also possible, however, that patients may not be receiving the correct combinations of medications. Furthermore, it should be noted that no information is available on patient adherence to their medication. Medication adherence is recognized as a key factor in helping to achieve BP control and reducing cardiovascular events in patients with hypertension [23,24]. Increased use of single-pill combinations, which provide adherence benefits [25], could be considered by physicians in the region.

The observed rates of controlled hypertension in the study could also be related to factors such as patient age, region of habitation, education and lifestyle factors (e.g. BMI and abdominal obesity). However, given the overall low rate of controlled hypertension, these factors cannot be considered a full explanation. The higher rate of controlled hypertension observed in patients aged 18 to less than 30 years (∼53%) compared with older patients (∼35–40%) may be attributed to young adults having milder hypertension, in conjunction with many of them being treatment naïve and hence showing better responses.

Some limitations of this study should be acknowledged. A common problem when taking BP measurements in the clinical setting is the ‘white-coat effect’, in which patients’ BP measurements may not be truly reflective of their actual BP in a more relaxed environment. Hence, this may have led to an overestimation of the prevalence of hypertension in the study. Ambulatory BP measurements, which can help to overcome the issue of white-coat hypertension, were not used in the present study. Variations in the types and calibrations of BP-measuring devices could also have been a source of error (given the large number of study centres involved) contributing to incorrect detections of hypertension in some participants. In addition, inaccuracies could have arisen because data were collected by noncardiologists. This factor should, however, be minimal owing to supervision of the study by cardiologists. It should also be emphasized that the data presented in the ETHNA study originated from patients attending primary care physicians in North Africa, and that this population does not necessarily reflect the general population. In particular, men and individuals living in rural areas may be underrepresented. Overall, the above limitations are quite common in all studies of this nature and are unlikely to have a significant impact on the overall trends identified here, especially considering the large sample size. Additionally, the calculations of age-adjusted and sex-adjusted rates of hypertension assist in making comparisons with the general population and other studies.

In conclusion, this study indicates that hypertension is highly prevalent and may be ineffectively treated in North Africa. In addition, the prevalence of cardiovascular risk factors is high in the residents of this region. This knowledge provides an opportunity to implement strategies to improve the situation. Clearly, there is a need to increase awareness of hypertension and cardiovascular disease in the region and to encourage establishment of healthy lifestyles. Primary care physicians have a particularly important first-line role to play in the diagnosis and management of hypertension. There is also a need for medical practitioners in the region to increase their knowledge of hypertension treatment guidelines to ensure that treatment is optimized. Increased focus on patient adherence to medication may also be required.

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ACKNOWLEDGEMENTS

The authors thank Dr Nadia Adib (previously employed by Novartis Pharma) who contributed to the study design and conduct. The authors also thank Dr Steven Inglis (PhD) of Oxford PharmaGenesis Ltd, UK, who provided medical writing support, including preparing an outline and first draft of the manuscript based on teleconferences and correspondence with the authors, and collating comments from the authors on first and subsequent drafts. Funding for medical writing support was provided by Novartis Pharma. The authors take full responsibility for the content of the article.

This work was funded by Novartis Pharma Maroc SA.

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Conflicts of interest

C.N. received financial support for designing, analysing and reporting the results of this study. M.A. received a consulting fee for contributing to the conception and design of this study. L.N., O.K. and V.B. are employees of Novartis Pharma, Morocco. H.M. is an employee of Novartis Pharma Services AG, Tunisia. F.B. and K.M. are employees of Novartis Pharma Services AG, Algeria. M-T.C. and R.B. have no conflicts of interest to declare.

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List of investigators

Algeria: Dr Baziz Belkacem; Dr Ait Benali Farid; Dr Larab Nadia; Dr Abbas Abdennour; Dr Abdelfettah Saddek; Dr Abdelhafid Ouennought; Dr Abdelouahab Wahiba; Dr Abdessemed Dhikra; Dr Abdi Rachid; Dr Adel Djoudi; Dr Ahmed Bouchetara; Dr Aissani Ahmed; Dr Akkouche F; Dr Ali Diaf; Dr Alitouche Smail; Dr Allal Saidi Zineb; Dr Allam Baya; Dr Allouti Moussa; Dr Amine Djebbari; Dr Arhab Farida; Dr Aribi Amel; Dr Atmane Habib; Dr Azibi Akri; Dr Beghoul Mourad; Dr Belamrif Fouzia; Dr Belaoui Mohammed; Dr Belkacem Abdelaziz; Dr Bellouche Zahida; Dr Benabdellah Karima; Dr Benadda Abed; Dr Benalioua Lynda; Dr Benariba R; Dr Benbrahim Med; Dr Benidir Med Rachid; Dr Benjeddou Ridha; Dr Benzahra Leulmi K; Dr Berkani Djamel Eddine; Dr Berkani Meriem; Dr Bouazza Mohamed; Dr Bouchetita Soufiane; Dr Boudekhani Ismail; Dr Bouderbala Sihem Latifa; Dr Boudjabi Samir; Dr Boudjouref Saliha; Dr Bouhadja Lazhar; Dr Bouhamed Abdel Illeh; Dr Brahim Cherrared; Dr Chekourou; Dr Chekroun Djamila; Dr Choutri Assia; Dr Derguini Nacerdine; Dr Dib Allal; Dr Djabelarbi Djamel; Dr Dlali Yamine; Dr F Boumaiza; Dr Farsi Abdelkader; Dr Fatnassi Belkacem; Dr Ferrad Mohamed; Dr Gadi Med Larbi; Dr Gassem Hacene; Dr Ghalem Saber; Dr Ghanem Meriem; Dr Ghedbane Nadia; Dr Hadji Tarik; Dr Halima Cheranti; Dr Hamlaoui Said; Dr Hamza Mahfoudh; Dr Hasnaoui Mohammed; Dr Ighili Mohamed; Dr Inal-Bendimred Assia; Dr K Ould Mohammed; Dr Kadour Daouadji; Dr Kamel Bourouis; Dr Karim Toubal; Dr Kebdani Hamed; Dr Kefkaf Mohamed; Dr Kerchich Omar; Dr Kettane Abdenour; Dr Khalifa Maamar; Dr Khassir Ahmed; Dr Khati S; Dr Khelil Abderahmane; Dr Korso Feciane Zineb; Dr L Boufferache; Dr Lalout Tarik; Dr Laouarem Bouadam Habiba; Dr Layadi Abdelaziz; Dr Mahjouba Ep Saad; Dr Mahmoudi Abdelaziz; Dr Mahtal Abdelhakim; Dr Maraf Hachemi; Dr Meddeber Siham Naima; Dr Menasria D; Dr Mihoubi Ahmed; Dr Mihoubi Mohamed; Dr Mohamadi Seddik; Dr Mohamed Elhassar; Dr Mokeddem Mohamed; Dr Mouhammedi Kamel; Dr Nacib Brahim; Dr R Mehidi; Dr S Adjali; Dr S Ait Mohand Said; Dr S Haouara Boubekeur; Dr Saadudi; Dr Said Cgerif Faouzia; Dr Seddik Bouchouicha Ahmed; Dr Smari Abdelhafid; Dr Soualhi Omar; Dr Taleb Mohamed; Dr Y Boulben; Dr Yamina Smati; Dr Z Megateli; Dr Zebar Nacereddine; Dr Ziane Soraya; Dr Hammouche Safia; Dr Gueddoum Salima; Dr Ifrah Larbi; Dr Achour Nee Boughanem Samiha; Dr Saadi Fatima.

Morocco: Dr El Azrak Abdelilah; Dr Abdelaziz Benazzouz; Dr Abdelaziz Hassanain; Dr Abdelilah Bouzoubaa; Dr Abdellah Alaoui; Dr Abderahim Zaanouni; Dr Abdessamad El Fahsse; Dr Aberrrazzak Serghini; Dr Abouabdallah Mohammed Elhabib; Dr Achibei Abdellafid; Dr Adnane Elhassan; Dr Ahlam Hamzaoui; Dr Ahmed Benboujida; Dr Alaoui Mdaghri Said; Dr Ammor Mohamed; Dr Anbari Abdelaziz; Dr Arrif Salah; Dr Assal Mohamed; Dr Azizi Fatima; Dr Azzeddine Zerouali; Dr Bachar Mustapha; Dr Bahssine Mohamed; Dr Baloul Bennani N; Dr Belhaj Khalid; Dr Benabdellah Samir; Dr Benghazi Azelarab; Dr Benkirane Mouna; Dr Bennani Abdelhamid; Dr Benseddik Amina; Dr Bhihi Abdelghafour; Dr Bouayad Lhassan; Dr Bouzbida Omar; Dr Chaal Mohamed; Dr Chbihi M’hamed; Dr Cheddad El Mostafa; Dr Dalila Alaoui Mharchi; Dr Darraz Houda; Dr Douhi Mohhamaed; Dr El Alouani Med; Dr El Bachir Sedrati; Dr El Jamali Abdelaziz; Dr El Mazouni Mohamed; Dr Elalami Farida; Dr Elallam Rachida; Dr Ellebbar Abdelkrim; Dr Errarhay Abdelaziz; Dr Essoubi Abderrrahim; Dr Fouad Lamrini; Dr Fouzia Chleh; Dr Ghailane Said; Dr Gmira Azzedine; Dr Grine Mustapha; Dr Habbazi Abderrezak; Dr Hadj Fouad Berdai; Dr Hajji Said; Dr Hamamsi Khalid; Dr Hamid Issiali; Dr Hassan Benmansour; Dr Hicham Fennich; Dr Hmamouche Amina; Dr Jaghalef Bensaid Amina; Dr Jamalddine Harour; Dr Janati Idrissi Abdellatif; Dr Kabbourim Mohamed; Dr Kouhen Mohamed Kamal; Dr Lahla Abderhamid; Dr Lakhnati Fatima; Dr Latifa Ratib; Dr Leon Ramon; Dr M Bouabdellaoui; Dr M Ben Cherif Ouedghiri; Dr Mbarek Rmili; Dr M’chich Alami Fatima-Zohra; Dr Mohamed Atik; Dr Mohamed Bokhari Khomsi; Dr Mohammadine Abdellah; Dr Mohammed El Harrak; Dr Moubir Maria; Dr Mouhamed Boughlam; Dr Moumen El Kabir; Dr Moumene Malika; Dr Nadir Nezha; Dr Rachida Hadoud; Dr Rahmani Abdenacel; Dr Riblaoui Najat; Dr Rizki Abdelghani; Dr Rochd Driss; Dr Saad Mrabet; Dr Sadik Fouzia; Dr Safi-Eddine Abdelkrim; Dr Sahraoui Mouhamed Yassin; Dr Said Gzouli; Dr Samia Bellouki; Dr Smiri Omar; Dr Souhail Abdelkader; Dr Squali Med; Dr Talbis Sif Eddine; Dr Touabi Fatiha; Dr Yazami Idrissi Mohamed; Dr Zahraoui Ali; Dr Zenjari Afifa; Dr Zidi Lahcen; Dr El Baz Mohamed; Dr Erroussafi El Miloudi; Dr Haddad Hachimi Med; Dr Haida Lahsen; Dr Jamil Aicha; Dr Mustapha Rassi; Dr Wifak Malika.

Tunisia: Dr Ahmed Joudi; Dr Aissa Mohamed; Dr Annaifer Wajdi; Dr Awatef Bouchaara Ghanoudi; Dr Baghdadi Badreddine; Dr B’chir Mohamed; Dr Ben Arbia Hamadi; Dr Ben Chaabane Kaïs; Dr Ben Chaabane Lotfi; Dr Ben Saad Abdelhamid; Dr Ben Said Hafedh; Dr Benammar Bechir; Dr Berrabam Med Mounir; Dr Bessaïes Mahmoud; Dr Blaich Khalid; Dr Boumaiza Jamal; Dr Bousnina Mohamed; Dr Chaabouni Manaf; Dr Chadia Sidhoum; Dr Cherif Fakhreddine; Dr Debbabi Adel; Dr Djmel Adel; Dr Dkan Boulbeba; Dr Fakhfak Tarak; Dr Fekih Manaf; Dr Guermaz Seddik; Dr Guermazi Habib; Dr Hatira Abdellaziz; Dr Hicham Ben Jaafar; Dr Jerbi Mounir; Dr Jerbi Najib; Dr Kamoun Ridha; Dr Karoui Med Cherif; Dr Karoui Mounir; Dr Kotti Raouf; Dr Kouki Sadok; Dr Kraiem Taoufik; Dr Lassaad Riachi; Dr Mahfoudh Mehdi; Dr Makni Samia; Dr Mohamed Kotti; Dr Moussa Najoua; Dr Mustapha Driss; Dr Nourer Mohamed Salah; Dr Rhouma Mohamed; Dr Rkik Samir; Dr Sahli Med Ridha; Dr Sahnoun Samir; Dr Samir Lakhal; Dr Sejil Mounir; Dr Slim Khader; Dr Sondes Ghariani Ammar; Dr Tanoubi Mohamed; Dr Thameur Ben Said; Dr Tira Hedi; Dr Zaiter Riadh; Dr Zheni Mohamed Slim; Dr Zmandar Chedly; Dr Drar Hayet; Dr Tanboura Slim.

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Reviewer's Summary Evaluations Reviewer 1

The strengths of this report from three countries in North Africa include a large (28 500 patients) and contemporary (2008–2009) survey of hypertension prevalence, treatment and control in primary care settings. The delineation of blood pressure into nine categories is instructive as are the data on prevalence of target organ damage and clinical complications associated with hypertension. While the study population is clinic based, the authors have made a commendable effort to extrapolate to prevalence data to the broader community. The study limitations include lack of standardized equipment for blood pressure measurement and reliance on chart review to assess comorbidities, target organ damage and clinical cardiovascular events without uniform definitions.

The findings show that the vast majority of hypertensive patients are treated (88%) but that control is comparatively low (∼36%). The findings have important implications for improving hypertension control within primary care settings in North Africa.

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Reviewer 2

The current study identifies a high prevalence of hypertension in North Africa and highlights the important issue of hypertension under-diagnosis and ineffective treatment in this region. The main strengths of this paper include the very large sample size of 28 500 participants as well as subgroup analyses of hypertension prevalence and control by sociodemographic factors such as age, gender, education, and urbanization status. Although an attempt is made to adjust prevalence estimates to that of the overall population, the use of a clinic-based sample may not be representative of the entire population residing in Algeria, Morocco, and Tunisia.

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Cited By:

This article has been cited 1 time(s).

Bmc Cardiovascular Disorders
Hypertension awareness, treatment and control in Africa: a systematic review
Kayima, J; Wanyenze, RK; Katamba, A; Leontsini, E; Nuwaha, F
Bmc Cardiovascular Disorders, 13(): -.
ARTN 54
CrossRef
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Keywords:

antihypertensive; blood pressure; cardiovascular disease; controlled hypertension; epidemiology; hypertension; hypertension risk; North Africa

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