Yackoob K. Seedat

Hypertension in Sub-Saharan African Populations

Background— Hypertension in sub-Saharan Africa is a widespread problem of immense economic importance because of its high prevalence in urban areas, its frequent underdiagnosis, and the severity of its complications. Methods and Results— We searched PubMed and relevant journals for words in the title of this article. Among the major problems in making headway toward better detection and treatment are the limited resources of many African countries. Relatively recent environmental changes seem to be adverse. Mass migration from rural to periurban and urban areas probably accounts, at least in part, for the high incidence of hypertension in urban black Africans. In the remaining semirural areas, inroads in lifestyle changes associated with “civilization” may explain the apparently rising prevalence of hypertension. Overall, significant segments of the African population are still afflicted by severe poverty, famine, and civil strife, making the overall prevalence of hypertension difficult to determine. Black South Africans have a stroke rate twice as high as that of whites. Two lifestyle changes that are feasible and should help to stem the epidemic of hypertension in Africa are a decreased salt intake and decreased obesity, especially in women. Conclusions— Overall, differences from whites in etiology and therapeutic responses in sub-Saharan African populations are graded and overlapping rather than absolute. Further studies are needed on black Africans, who may (or may not) be genetically and environmentally different from black Americans and from each other in different parts of this vast continent.

South African Hypertension Guideline 2011

OUTCOMES Extensive data from randomised controlled trials have shown the benefit of treating hypertension. The target blood pressure (BP) for antihypertensive management is systolic <140 mmHg and diastolic <90 mmHg with minimal or no drug side-effects; however, stricter BP control is required for patients with end-organ damage, co-existing risk factors and co-morbidity, e.g. diabetes mellitus. The reduction of BP in the elderly and in those with severe hypertension should be achieved gradually over 1 month. Co-existent risk factors should also be controlled. BENEFITS Benefits of management include reduced risks of stroke, cardiac failure, chronic kidney disease and coronary heart disease. RECOMMENDATIONS The correct BP measurement procedure is described, and evaluation of cardiovascular risk factors and recommendations for antihypertensive therapy are stipulated. The total cardiovascular disease risk profile should be determined for all patients to inform management strategies. Lifestyle modification and patient education are cornerstones in the management of every patient. Major indications, precautions and contra-indications to each recommended antihypertensive drug are listed. Combination therapy should be considered ab initio if the BP is ≥ 20/10 mmHg. First-line drug therapy for uncomplicated hypertension includes low-dose thiazide-like diuretics, calcium channel blockers (CCBs) or angiotensin-converting enzyme inhibitors (ACE-Is) (or ARBs - angiotensin II receptor blockers). If the target BP is not obtained, a second antihypertensive should be added from the aforementioned list. If the target BP is still not met, the third remaining antihypertensive agent should be used. In black patients either thiazide-like diuretics or CCBs can be used initially, because response rates are better than with ACE-Is or β-blockers. In treating resistant hypertension, a centrally acting drug, vasodilator, α-blocker, spironolactone or β-locker should be added. This guideline includes management of specific situations, i.e. hypertensive emergency and urgency, severe hypertension with target organ damage, hypertension in diabetes mellitus, resistant hypertension, fixed drug combinations, new trials in hypertension, and interactions of antihypertensive agents with other drugs. VALIDITY The guideline was developed by the Southern African Hypertension Society.

Coping with urbanization: A cardiometabolic risk? The THUSA study

An assessment of specific coping styles in rural-urban Africans is done to evaluate its contribution as cardiometabolic risk factor. In total, 608 apparently healthy Africans were included in a cross-sectional comparative study from the North-West Province in South Africa. The adapted and translated COPE Questionnaire classified participants according to their responses into active (AC) or passive (PC) copers. Fasting resting metabolic syndrome (MS) indicators using the WHO definition (glucose, high density lipoproteins, waist/hip ratio, hypertension prevalence, and triglyceride) and associated MS values, i.e. fibrinogen were obtained. The Finapres recorded resting blood pressure continuously. Co-variates for all statistical analyses included age, body mass index (BMI) and lifestyle factors (alcohol consumption, smoking habits and physical activity). The only MS values prevalent in urbanized participants were higher hypertension prevalence rates and fibrinogen (women only) compared to their rural counterparts. Adding coping styles, it was mainly the urbanized AC participants that indicated higher MS values (hypertension prevalence, glucose and fibrinogen) when compared to their rural and PC counterparts. In conclusion, urbanization is associated with enhanced blood pressure and fibrinogen (women) values only. Coping as cardiometabolic risk is accentuated in the urbanized AC group, especially the men. The urbanized AC group with their higher blood pressure values and more MS indicators appears to have behaviorally an AC style but physiologically a dissociated AC style.

Why do hypertensive patients of African ancestry respond better to calciumblockers and diuretics than to ACE inhibitors and β-adrenergic blockers? Asystematic review

BackgroundClinicians are encouraged to take an individualized approach when treatinghypertension in patients of African ancestry, but little is known about whythe individual patient may respond well to calcium blockers and diuretics,but generally has an attenuated response to drugs inhibiting therenin-angiotensin system and to β-adrenergic blockers. Therefore, wesystematically reviewed the factors associated with the differential drugresponse of patients of African ancestry to antihypertensive drugtherapy.MethodsUsing the methodology of the systematic reviews narrative synthesis approach,we sought for published or unpublished studies that could explain thedifferential clinical efficacy of antihypertensive drugs in patients ofAfrican ancestry. PUBMED, EMBASE, LILACS, African Index Medicus and the Foodand Drug Administration and European Medicines Agency databases weresearched without language restriction from their inception through June2012.ResultsWe retrieved 3,763 papers, and included 72 reports that mainly considered the4 major classes of antihypertensive drugs, calcium blockers, diuretics,drugs that interfere with the renin-angiotensin system and β-adrenergicblockers. Pharmacokinetics, plasma renin and genetic polymorphisms did notwell predict the response of patients of African ancestry toantihypertensive drugs. An emerging view that low nitric oxide and highcreatine kinase may explain individual responses to antihypertensive drugsunites previous observations, but currently clinical data are verylimited.ConclusionAvailable data are inconclusive regarding why patients of African ancestrydisplay the typical response to antihypertensive drugs. In lieu ofbiochemical or pharmacogenomic parameters, self-defined African ancestryseems the best available predictor of individual responses toantihypertensive drugs.

South African hypertension practice guideline 2014 : review article

Summary Outcomes Extensive data from many randomised, controlled trials have shown the benefit of treating hypertension (HTN). The target blood pressure (BP) for antihypertensive management is systolic < 140 mmHg and diastolic < 90 mmHg, with minimal or no drug side effects. Lower targets are no longer recommended. The reduction of BP in the elderly should be achieved gradually over one month. Co-existent cardiovascular (CV) risk factors should also be controlled. Benefits Reduction in risk of stroke, cardiac failure, chronic kidney disease and coronary artery disease. Recommendations Correct BP measurement procedure is described. Evaluation of cardiovascular risk factors and recommendations for antihypertensive therapy are stipulated. Lifestyle modification and patient education are cornerstones of management. The major indications, precautions and contra-indications are listed for each antihypertensive drug recommended. Drug therapy for the patient with uncomplicated HTN is either mono- or combination therapy with a low-dose diuretic, calcium channel blocker (CCB) and an ACE inhibitor (ACEI) or angiotensin receptor blocker (ARB). Combination therapy should be considered ab initio if the BP is ≥ 160/100 mmHg. In black patients, either a diuretic and/or a CCB is recommended initially because the response rate is better compared to an ACEI. In resistant hypertension, add an alpha-blocker, spironolactone, vasodilator or β-blocker. Validity The guideline was developed by the Southern African Hypertension Society 2014©.

A study of urinary sodium and potassium excretion rates among urban and rural Zulus and Indians.

A study was carried out to evaluate the relationship between blood pressure, plasma renin activity, serum aldosterone and patterns of urinary sodium and potassium excretion rates in urban Zulus, rural Zulus and Indians in order to explain the high prevalence of hypertension in the urban adult Zulu (25%) compared to the rural adult Zulu (10%). Urinary sodium and potassium were not significantly different between urban and rural Zulus. There was no association between sodium excretion and blood pressure. Urinary potassium correlated negatively with blood pressure in rural Zulus and Indians but not in urban Zulus. The urinary sodium:potassium ratio was significantly lower in rural Zulus than in urban Zulus. The sodium:potassium ratio of Indians was not significantly different from that of Zulus. Plasma renin activity levels were significantly lower in urban than in rural Zulus. This difference is an enigma but may be due to an environmental factor. Serum aldosterone correlated positively with plasma renin activity and negatively with the urinary sodium:potassium ratio.

Systematic review: antihypertensive drug therapy in patients of African and South Asian ethnicity

Despite the large differences in the epidemiology of hypertension across Europe, treatment strategies are similar for national populations of white European descent. However, hypertensive patients of African or South Asian ethnicity may require ethnic-specific approaches, as these population subgroups tend to have higher blood pressure at an earlier age that is more difficult to control, a higher occurrence of diabetes, and more target organ damage with earlier cardiovascular mortality. Therefore, we systematically reviewed the evidence on antihypertensive drug treatment in South Asian and African ethnicity patients. We used the Cochrane systematic review methodology to retrieve trials in electronic databases including CENTRAL, PubMed, and Embase from their inception through November 2015; and with handsearch. We retrieved 4596 reports that yielded 35 trials with 7 classes of antihypertensive drugs in 25,540 African ethnicity patients. Aside from the well-known blood pressure efficacy of calcium channel blockers and diuretics, with lesser effect of ACE inhibitors and beta-blockers, nebivolol was not more effective than placebo in reducing systolic blood pressure levels. Trials with morbidity and mortality outcomes indicated that lisinopril and losartan-based therapy were associated with a greater incidence of stroke and sudden death. Furthermore, 1581 reports yielded 16 randomized controlled trials with blood pressure outcomes in 1719 South Asian hypertensive patients. In contrast with the studies in African ethnicity patients, there were no significant differences in blood pressure lowering efficacy between drugs, and no trials available with mortality outcomes. In conclusion, in patients of African ethnicity, treatment initiated with ACE inhibitor or angiotensin II receptor blocker monotherapy was associated with adverse cardiovascular outcomes. We found no evidence of different efficacy of antihypertensive drugs in South Asians, but there is a need for trials with morbidity and mortality outcomes. Screening for cardiovascular risk at a younger age, treating hypertension at lower thresholds, and new delivery models to find, treat and follow hypertensives in the community may help reduce the excess cardiovascular mortality in these high-risk groups.

Blood-pressure-related disease is a global health priority.

I n global-health politics, cardiovascular disease is the elephant in the room—a massive problem that few want to acknowledge and even fewer want to tackle. In [a recent issue of] Lancet, Carlene Lawes and colleagues, on behalf of the International Society of Hypertension, estimate that bloodpressure-related diseases cause about half this burden, killing around 8 million people each year.1 Low-income and middleincome countries shoulder about 80% of the cardiovascular-disease burden, half of which is in people of working age. This situation was all predicted a decade ago by the Global Burden of Disease Project,2 but none of the major healthdevelopment funds—including the Bill & Melinda Gates Foundation, the World Bank, the major regional development banks, and major bilateral donors—have made any substantive or sustained effort to address this issue. Similarly, none of the major international drug companies have offered material assistance in this

Review: Diabetes mellitus in South African Indians

Diabetes mellitus is common in the South Asian population residing in the Indian diaspora. Cardiovascular disease is a major cause of death in the Indians of South Africa. This study reviews the ep...

Why is control of hypertension in sub-Saharan Africa poor?

In sub-Saharan Africa (SSA) in 2010, hypertension (defined as systolic blood pressure ≥ 115 mmHg) was the leading cause of death, increasing 67% since 1990. It was also the sixth leading cause of disability, contributing more than 11 million adjusted life years. In SSA, stroke was the main outcome of uncontrolled hypertension. Poverty is the major underlying factor for hypertension and cardiovascular disease. This article analyses the causes of poor compliance in the treatment of hypertension in SSA and provides suggestions on the treatment of hypertension in a poverty-stricken continent.In sub-Saharan Africa (SSA) in 2010, hypertension (defined as systolic blood pressure ≥ 115 mmHg) was the leading cause of death, increasing 67% since 1990. It was also the sixth leading cause of disability, contributing more than 11 million adjusted life years. In SSA, stroke was the main outcome of uncontrolled hypertension. Poverty is the major underlying factor for hypertension and cardiovascular disease. This article analyses the causes of poor compliance in the treatment of hypertension in SSA and provides suggestions on the treatment of hypertension in a poverty-stricken continent.