Factor analysis of possible risks for hypertension in a black South African population

Abstract

To date only a small number of studies have investigated the pattern of associations within a set of hypertension risks. The objective of this study was therefore to examine the interrelation of main hypertension risks in an African population by using factor analysis in order to detect underlying risk patterns. Subjects aged 16-70 years (N ¼ 963) were recruited from 37 randomly selected sites throughout the North West Province during 1996-1998. Exclusion criteria were pregnancy, lactation, casual visitors, drunkenness and treatment for chronic diseases, such as hypertension. Subjects with blood pressures exceeding 140/90 mmHg were classified as hypertensive. Children aged 10-15 years were also recruited from 30 randomly selected schools during 2000-2001 (N ¼ 694). Children were classified as hypertensive when an average systolic or diastolic blood pressure greater than or equal to the 90th percentile for age and sex was encountered, while correcting for height. The following hypertension risks were measured: urbanisation, obesity, plasma fibrinogen, lipids, insulin, serum gamma glutamyl-transferase, dietary intake, smoking and alcohol consumption. From 23 risks the factor analysis disclosed five factors that explained 56.2% of the variance in the male and 43.5% of the variance in the female group: an urban malnutritional phenomenon, the metabolic syndrome X, a hypercholesterolaemic and obesity complex, an alcoholic hypertriglyceridaemia, and central and peripheral cardiovascular hypertensive effects. In conclusion, South Africans migrating from rural to urban areas adapt to a new lifestyle with numerous risks, resulting in conditions like malnutrition, the metabolic syndrome X, dyslipidaemia, alcoholism, obesity and increased peripheral vascular resistance. For successful prevention of hypertension in a population in transition, a whole risk pattern should be corrected, rather than an individual risk by implementing lifestyle modification programmes.

The risk factors for elevated blood pressure and how to address cardiovascular risk factors: a review in paediatric populations

“…The prevalence of hypertension in sub-Saharan Africa ranged 0-12.5% for boys and 0-21.5% for girls ( Table 1). The highest prevalence rate recorded was 21.5% 31 for girls and 12.5% for boys, 32 whereas Steyn et al 30 recorded the highest total prevalence rate of 22.3% for both boys and girls in urban South African children. Misra et al 19 recorded the highest (20.0%) prevalence of BP for boys in the Asian region followed by Smith and Rinderknecht 14 in the United Staes (13.2%).…”

“…In general, the studies cited in this review classified the children as hypertensive based on the the guidelines for hypertension. 12,13,31,32,30,[33][34][35] Frontini et al 24 and Barger and Muldoon 25 classified children as hypertensive based on the 140/90 mm Hg recommendation of the WHO. It is clear from the cutoff point of these two studies together with the study of van der Sande et al 22 who used 160/95 mm Hg that the situation might be worse than it is reported in their respective area.…”

Should obesity be blamed for the high prevalence rates of hypertension in black South African women?

“…[1][2][3] As a result, black South Africans have a stroke mortality rate twice as high as that of Caucasians. 1 Multiple causative factors have been proposed to explain the high hypertension prevalence, including lower plasma renin levels, 4 sodium abnormalities, 5 epithelial sodium channel changes, 4 altered genes regulating the renin-angiotensin-aldosterone system, 4 increased peripheral vascular resistance 1 as well as increasing obesity prevalence.…”

Obesity and overweight in South African primary school children—the Health of the Nation Study

“…[1][2][3][4] In South Africa it has been suggested that urbanisation 5 is associated with an increased risk of becoming overweight or obese. 6,7 Indeed, high levels of obesity have been identified among urbanised South Africans, particularly among black women. 5,7,8 The World Health Organization 9 has identified an increase in childhood obesity in developed countries and a high prevalence of childhood obesity has been reported in developing regions such as in Latin America.…”