Coronary heart disease risk factors in a rural and urban Orange Free State black population

To determine and compare the prevalence of ischaemic heart disease (IHD) risk factors in a rural and an urban black population.

A survey to determine the prevalence of hypertension, diabetes mellitus, smoking, obesity, central obesity and dyslipidaemia in black subjects 25 years and older.

The indigenous black populations of QwaQwa and Mangaung.

A random sample of 950 households was selected from each area. From each household an unrelated male and/or female subject was selected in a standardised way. From QwaQwa 853 subjects (279 men and 574 women) and from Mangaung 758 subjects (290 men and 468 women) participated in the study. The response rate was 68% and 62% respectively for QwaQwa and Mangaung.

Few urban-rural differences in the prevalence of IHD risk factors were found in this study. A low prevalence of clustering of major IHD risk factors was noted.

The age- and sex-adjusted prevalences of hypertension were 29% in QwaQwa and 30.3% in Mangaung. Diabetes was present in 4.8% of the QwaQwa sample and 6% of the Mangaung sample. The prevalence of heavy smoking in the Mangaung sample was almost double that of the QwaQwa sample and mostly confined to men. High-risk hypercholesterolaemia was present in 12.5% of QwaQwa and 6% of Mangaung men in the 25-34-year age group. The corresponding figures for moderate-risk hypercholesterolaemia were 34% and 44.8% and both levels of risk declined with increasing age. The mean body mass index of women in both samples exceeded 25 kg/m2.

All the elements for a potential epidemic of atherosclerotic cardiovascular disease are present in the study populations. The similarity of findings in the two samples may be indicative of the advanced stage of urbanisation and westernisation of the rural group. It is alarming that subjects in the younger age groups tended to have the highest prevalences of moderate and even high-risk hypercholesterolaemia.