South African Hypertension Society commentary on the American College of Cardiology/American Heart Association hypertension guidelines.

In late 2017, the publication of the new American College of Cardiology (ACC)/American Heart Association (AHA) hypertension guidelines created considerable controversy. The threshold for hypertension was redefined as > 130/80 mmHg and target blood pressure < 130/80 mmHg. The purpose of this commentary is to give clarity on the position of the Southern African Hypertension Society (SAHS). In South Africa more than 90% of hypertensives are not controlled at < 140/90 mmHg. Furthermore, by redefining hypertension to a level of 130/80 mmHg, this will significantly increase the prevalence of hypertension by 43%. The new targets will necessitate greater use of health services for increased health visits to monitor patients, greater use of antihypertensives to achieve the lower target, and increased use of laboratory services to monitor for adverse effects. It is the position of SAHS that the new definition and targets are not relevant to low- and middle-income countries such as South Africa, the threshold for hypertension remains at 140/90 mmHg, and a universal target is < 140/90 mmHg for all categories of hypertension.

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.

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.

Guanfacine alone and in combination therapy in the treatment of moderate and severe hypertension.

This study of guanfacine in 27 patients suffering from moderate-to-severe hypertension showed a satisfactory blood pressure control in 26 patients. Twenty-one of the 27 patients completed a one-year clinical trial with good blood pressure response. The new drugs, acting through the stimulation of the central alpha-adrenoceptors, are useful in patients suffering from moderate-to-severe hypertension. They are a good alternative to adrenergic neuron-blocking drugs, methyldopa, or beta-blockers, and useful in patients with refractory hypertension where conventional therapy has failed.

Efficacy and tolerability of nisoldipine coat-core formulation in the treatment of essential hypertension: The South African Multicenter ANCHOR Study. Ambulatory Nisoldipine Coat-Core Hypertension Outpatient Response (ANCHOR) Investigators.

A double-blind, placebo-controlled, multicenter trial was undertaken to assess the antihypertensive efficacy and tolerability of a controlled-release (Coat-Core [CC] tablet) formulation of the second-generation dihydropyridine calcium channel antagonist, nisoldipine. Of the 208 patients with mild-to-moderate essential hypertension, two were excluded from the main efficacy analysis, and the rest randomized into one of four treatment groups, to receive either placebo, or nisoldipine CC at doses of 10, 20, or 30 mg once daily for 6 weeks, following a 4-week placebo run-in period. Blood pressure measurements (supine, standing, diastolic, and systolic) were taken at trough plasma levels, 24 h after previous dosing at 2-week intervals throughout the study. Adverse events and laboratory parameters (plasma lipid and glucose levels, and thyroid function) were monitored. All three doses of nisoldipine CC lowered blood pressure, as compared with placebo, 24 h after dosing. At endpoint (after 6 weeks) mean changes in supine blood pressure from baseline were (systolic/diastolic) 0.9/-2.3, -8.0/-5.5, -16.9/-9.0, and -15.0/-10.3 mm Hg for the groups assigned to placebo and nisoldipine CC 10, 20, and 30 mg, respectively. The response rates were 35%, 47%, and 63% for nisoldipine CC 10, 20, and 30 mg, respectively. Twenty-four-hour ambulatory blood pressure monitoring showed that nisoldipine CC effectively controlled blood pressure throughout the dosing interval. No change in heart rate was seen for all three doses of nisoldipine CC over the 24-h dosing interval. Nisoldipine CC was at least as effective in black patients as in whites. Generally adverse events were not increased, except for peripheral edema, with rates of 7% in placebo, and 6%, 9%, and 19%, respectively, in those receiving nisoldipine CC 10, 20, or 30 mg daily. There were no clinically significant changes in blood lipids, blood glucose, or thyroid function. In conclusion, once-daily nisoldipine CC at doses of 10 to 30 mg was an effective and well tolerated antihypertensive agent, providing 24-h control of blood pressure without any increase in heart rate.

An evaluation of debrisoquine and mefruside in the treatment of hypertension in African and Indian patients.

A double-blind, crossover trial was carried out in 20 hypertensive patients (9 African and 11 Indian) to compare the effectiveness and tolerance of treatment with debrisoquin, mefruside, and a fixed-dose combination of the two drugs with placebo. Patients were treated initially with placebo for 2 weeks before being crossed-over to treatment for 4 weeks with each of the other regimens. Maximum daily dosages of the active drugs were 20 mg debrisoquin and 25 mg mefruside. Satisfactory hypotensive control, i.e. diastolic blood pressure less than or equal to 90 mmHg, was not achieved in any of the treatment periods. The best hypotensive response was obtained in African patients on mefruside. The combination of debrisoquin and mefruside did not produce the expected synergistic response. Few side-effects were reported. The failure of an adequate hypotensive response to debrisoquin in African and Indian patients could be due to a genetic difference in the hydroxylation of debrisoquin.

Prazosin combined with thiazide diuretic and beta-blocker in the treatment of hypertension.

In a study of 10 patients suffering from hypertension the results showed that combination treatment with prazosin, cyclopenthiazide and a beta-blocker produced a significant fall in blood pressure. Side-effects such as palpitations, headache, syncope and drowsiness which may occur with prazosin alone were obviated by combining prazosin with a beta-blocker.

Prevalence of hypertension in the urban and rural Zulu.

In a house-to-house study of 994 urban Zulus the prevalence of hypertension according to WHO criteria was 25% (23% men, 27% women). In a rural Zulu study of 987 the prevalence age corrected to the urban distribution was 9.4% (8.7% men, 10% women). Thus there was a pronounced difference between the prevalence of hypertension in the urban and rural Zulu (p less than 0.0005). There was an earlier onset of hypertension in the urban compared with the rural Zulu. Contrasting biosocial factors in the urban and rural Zulu could explain the differences in prevalence. Our study suggests that hypertension is not a major health problem in rural Zulus. Large-scale case finding and intervention programmes should be confined to the urban black population of South Africa.

Nephrotic syndrome in the Africans and Indians of South Africa. A ten-year study.

The frequency of nephrotic syndrome was 0.2% of all medical admission records. A prospective study of 180 nephrotic patients was begun in 1966 and ended in 1976 and the clinical, biochemical and renal histological changes were studied. Unlike other studies of nephrotic syndrome in West and East Africa, in which malaria is believed to play an important aetiological part, this study in Durban was done in a malaria-free area. Most of the patients were between the ages of 12 and 30 years. The aetiology of the nephrotic syndrome was undetermined in 94% of the African patients and in 87% of the Indian patients. The most common histological pattern in both racial groups was proliferative glomerulonephritis, followed by membranous glomerulonephritis. Minimal change on light microscopy was rare. This has important implications from the therapeutic aspect because African patients suffering from nephrotic syndrome will not as a rule respond to steroids or cyclophosphamide therapy. An initial diastolic blood pressure greater than or equal to 110 mm Hg and a low serum complement were more common in proliferative glomerulonephritis. The serum gamma-globulin, though low, was raised compared with the normal serum gamma-globulin, in the white population. A difference in the serum lipoprotein patient between the two races was observed.

The prevalence of hypertension in 4,993 rural Zulus.

In a study of 4,993 rural Zulus the over-all prevalence of primary hypertension was 8.37% (females 8.78%, males 7.4%). The mean arterial pressure in relation to age and sex was not as high as in urban Zulus. A diastolic blood pressure of greater than or equal to 95 mm Hg was present in 4.99% of the subjects and 1.46% had a diastolic blood pressure of greater than or equal to 110 mm Hg. This study suggests that hypertension is not a major health problem in rural Zulus and that large case-finding and intervention programmes should be confined to the urban Black population of South Africa.

Is the pathogenesis of hypertension different in black patients?

There is a higher prevalence of hypertension in the urban black population of South Africa and the USA in comparison to whites living in the same geographical areas. Several factors including age, urbanisation, socioeconomic status and acculturation contribute to the differences in the prevalence of hypertension between blacks and whites. In addition there may be a genetic element. Biochemical differences in the lipid profile of the blacks in Sub-Saharan Africa may play an Important role in the lower incidence of coronary heart disease. Blacks have an abnormal transport mechanism of sodium. There are varying responses to antihypertensive drugs in blacks compared to whites. It is probable that with a better understanding of the pathogenesis of hypertension in blacks, we will be able to reduce the high prevalence, prevent complications and institute more effective treatment and control of hypertension.

Hypertension in developing nations in sub-Saharan Africa.

There is a rapid development of the 'second wave epidemic' of cardiovascular disease that is now flowing through developing countries and the former socialist republics. It is now evident from WHO data that coronary heart disease and cerebrovascular disease are increasing so rapidly that they will rank No. 1 and No. 5 respectively as causes of global burden by the year 2020. In spite of the current low prevalence of hypertensive subjects in some countries, the total number of hypertensive subjects in the developing world is high, and a cost-analysis of possible antihypertensive drug treatment indicates that developing countries cannot afford the same treatment as developed countries. Control of hypertension in the USA is only 20% (blood pressure <140/90 mm Hg). In Africa only 5-10% have a blood pressure control of hypertension of <140/90 mm Hg. There are varying responses to antihypertensive therapy in black hypertensive patients. Black patients respond well to thiazide diuretics, calcium channel blockers vasodilators like alpha-blockers, hydralazine, reserpine and poorly to beta-blockers, angiotensin-converting enzyme inhibitors and All receptor antagonists unless they are combined with a diuretic. A comprehensive cardiovascular disease (CVD) programme in Africa is necessary. There are social, economic, cultural factors which impair control of hypertension in developing countries. Hypertension control is ideally suited to the initial component on an integrated CVD control programme which has to be implemented. Primary prevention, through a population-based lifestyle linked programme, as well as cost-effective methods of detection and management are synergistically linked. The existing health care infrastructure needs to be orientated to meet the emerging challenge of CVD, while empowering the community through health education.

Hypertension and vascular disease in India and migrant Indian populations in the world.

The association of hypertension, diabetes mellitus and abnormal lipoprotein patterns suggests that this combination has a lethal effect with regard to vascular disease. It is therefore necessary to do something about the known lifestyle factors such as cigarette smoking, obesity and possibly a low fibre diet. The high incidence of ischaemic heart disease among emigrant Indians in South Africa and Trinidad, and the low incidence in blacks of South Africa and the West Indies, suggests that there may be different thresholds for susceptibility to disease in various ethnic groups, beyond which the risk factors begin to operate.

Hypertension in black South Africans.

Hypertension is a major disease in the black populations of sub-Saharan Africa and the USA. The prevalence of hypertension varies from 1-30% in the adult population. Differences in blood pressure (BP) between black and white patients have been documented. In this review genetic, endocrine and environmental characteristics, renal physiology and cardiac function are reviewed. Racial differences in renal physiology and socio-economic status seem to account for BP differences. Black hypertensive patients in sub-Saharan Africa are prone to cerebral haemorrhage, malignant hypertension, leading to uraemia and congestive heart failure, whereas coronary artery disease is relatively uncommon. Responses to antihypertensive drugs like the beta-blockers and the angiotensin-converting enzyme (ACE) inhibitors are poor unless these agents are combined with a thiazide diuretic. Black hypertensive patients respond best to diuretics, vasodilators or calcium channel blockers. A profiled approach to the treatment of hypertension in black patients is suggested.

Improvement in treatment of hypertension has not reduced incidence of end-stage renal disease.

Hypertension is an important cause of end-stage renal disease (ESRD) in the USA and in Sub-Saharan Africa. Antihypertensive therapy has led to a substantial decrease in incidence of stroke (42%) and to a lesser extent of myocardial infarction (16%), yet there has been an increase in hypertension related ESRD. In 1991, about 190 000 persons in the USA either underwent dialysis or received a transplant for ESRD. Hypertension was found to be the underlying cause in 29% of these patients, second only to diabetes mellitus (36%). Both in the USA and South Africa hypertension was found to be the most common cause of ESRD, but it is not clear whether this is related to the higher incidence and severity of hypertension in black people. Moreover blood pressure (BP) control in black patients does not necessarily lead to improved renal function. These findings suggest that factors other than BP elevation participate in the progression of nephrosclerosis. They include misdiagnosis, black race (socio-economic status, physiologic differences, severity of hypertension), BP control (adequate control of BP and type of antihypertensive therapy), and possibly other factors like genetics. The lack of reduction in ESRD may be that currently accepted standards for BP control are not adequate and that different antihypertensive agents affect glomerular haemodynamics in different ways. These factors need an in-depth analysis to improve the important public health issue of increasing morbidity and mortality from ESRD.

Risk factors leading to coronary heart disease among the black, Indian and white peoples of Durban.

This paper compares and contrasts the important risk factors which may predispose to coronary heart disease (CHD) in the Black, Indian and White peoples of Durban. CHD is very common the Whites and Indians in South Africa. In contrast CHD is still uncommon in the Blacks of South Africa. Indians living in South Africa have a higher prevalence of CHD compared to Indians in India.

Study of risk factors leading to coronary heart disease in urban Zulus.

Coronary heart disease (CHD) is still relatively uncommon in the black population of South Africa. We embarked on a study to determine the prevalence of risk factors leading to CHD in the black population of Durban. The study sample was selected from patients attending a dental clinic at a hospital. A total of 458 Zulus (age range 16-69 years) were studied. The prevalence of CHD was 2.4%. The prevalence percentage of selected risk factors were: hypertension (SBP > or = 140 mmHg and/or a DBP > or = 90 mmHg) was 28%, males 31.9%, females 25.4%; protective levels of high density lipoprotein cholesterol/total cholesterol (HDLC/TC) (> or = 20%) were 81.3%; diabetes, males 4.9%, females 2.9%; smoking > or = ten cigarettes per day, males 28.1%, females 3.4%; obesity, males 3.7%, females 22.6%. We have found the Minnesota Coding System for ECG changes of CHD and Rose questionnaire to be unreliable for eliciting CHD in Blacks. Hypercholesterolaemia is less common and this may explain the low incidence of CHD in Blacks. Epidemics of CHD as seen in the Indian, 'mixed' and white South Africans can still be prevented in the black population but preventive measures must be instituted rapidly.

Urinary levels of tissue kallikrein in the South African Black and Indian hypertensives.

It is accepted that Black subjects differ from White and Indian hypertensives in their response to hypotensive agents. Black hypertensives in the USA have a lower urinary tissue kallikrein (TK) excretion levels compared to White hypertensives. It has been suggested that Black patients respond better to thiazide diuretics compared to beta-blockers because thiazides increase whereas beta-blockers decrease tissue kallikrein excretion. This study compares the excretion of urinary TK in Black and Indian hypertensive and normotensive subjects. Urinary TK levels were measured with the selective, synthetic peptic substrate with the sequence of H-D-Val-Leu-Arg-pNA. Ten hypertensive patients on placebo therapy and 10 normotensive Black and Indian subjects provided three samples at weeks 0, 2 and 4 for the determination of urinary TK. The results were analysed using analysis of variance to compare the two racial groups. There were no significant differences in urinary TK values of the three bi-weekly individual samples. Urinary tissue kallikrein values (ng TK/microg protein) in Indian hypertensives were in general lower than Black hypertensives.

The prevalence of hypertension and the status of cardiovascular health in South Africa.

The population of South Africa is nearly 40 million and is growing at the rate of 2.5% per year. The population is 76.2% black, 13.3% white, 8.6% "mixed," and 2.6% Asian. The life expectancy (between 1985 and 1990) for whites was 69 years for males and 77 years for females; and for blacks, life expectancy was 61 years for males and 67 years for females. The major causes of death in blacks was accidents, poisoning and violence, which accounted for 14%. HIV/AIDS has reached epidemic proportions, and it is estimated that by the first decade of the next century between 18% and 27% of South African black adults will be infected. Diseases of the circulatory system claimed the most lives among whites (38.4%), Asians (34.1%), and the mixed group (21.8%). Coronary heart disease (CHD) was the major cause of death among whites and Asians in the circulatory system disease category and the main contributor to all causes of death. The CHD death rates of 165.3 and 101.2 per 100,000 population for whites and Asians, respectively, surpassed that of the "mixed" group (55.1 per 100,000); blacks had the lowest rate (5.3 per 100,000). Cerebrovascular disease is first among the "mixed" group, followed by whites and Asians, and then blacks (73.6, 62.5, and 36.5 per 100,000, respectively).

Antihypertensive Effect and Tolerability of Perindopril in Indian Hypertensive and Type 2 Diabetic Patients: 1-Year Randomised, Double-Blind, Parallel Study vs Atenolol.

OBJECTIVE: This study compared the antihypertensive effect and acceptability of a perindopril-based group with that of an atenolol-based group in Indian hypertensive type 2 (non-insulin-dependent) diabetic patients. DESIGN AND SETTING: 100 ambulant patients aged between 35 and 69 years were recruited into this monocentric, randomised, double-blind study in two parallel groups for 1 year after a 1-month washout period on placebo. The setting was a tertiary care institution. PATIENTS: All patients had stable, essential hypertension between 95mm Hg and 115mm Hg, type 2 diabetes with glycosylated haemoglobin (HbA(1C)) <12%, and albuminuria between 300mg and 3.5g/24 hours. There were 50 patients per treatment group and two patient population groups were studied, intention-to-treat (ITT) and per-protocol (PP). The former constituted all patients, whilst the latter included those without major protocol deviation and who completed the 12-month study. INTERVENTIONS: The study drugs were perindopril 4 to 8mg once daily or atenolol 50 to 100mg once daily. In each group therapeutic adjustment was planned by doubling the dose and then by the addition of hydrochlorothiazide 25mg daily. Nifedipine 30 to 60mg daily was subsequently added if the desired drop in blood pressure was not obtained. The ITT group was analysed by Student's t-test, and a 2-way analysis of variance was performed for the PP population. MAIN OUTCOME MEASURES: A comparison of the control of hypertension, biochemical abnormalities, blood sugar and adverse effects was performed in the atenolol group versus the perindopril group. RESULTS: On single-dose therapy after 1 month 17 patients (60%) had normal blood pressure [diastolic blood pressure (DBP)