Social drift of cardiovascular disease risk factors in Africans from the North West Province of South Africa: the PURE study

OBJECTIVE: This study examined whether the association between socio-economic status (SES) and cardiovascular disease (CVD) risk factors in black South Africans from the North West Province had shifted from the more affluent groups with higher SES to the less affluent, lower SES groups over a period of nine years. METHOD: Cross-sectional baseline data of 2 010 urban and rural subjects (35 years and older) participating in the Prospective Urban and Rural (PURE) study and collected in 2005 were analysed to examine the relationship of level of education, employment and urban or rural residence with dietary intakes and other CVD risk factors. These relationships were compared to those found nine years earlier in the Transition and Health during the Urbanisation of South Africans (THUSA) study conducted in the same area. RESULTS: The results showed that urban women had higher body mass index (BMI), serum triglyceride and fasting glucose levels compared to rural women and that both urban men and women had higher blood pressures and followed a more Westernised diet. However, rural men and women had higher plasma fibrinogen levels. The more highly educated subjects (which included both urban and rural subjects) were younger than those with no or only primary school education. Few of the risk factors differed significantly between education groups, except that more highly educated men and women had lower BMIs, and women had lower blood pressure and triglyceride levels. These women also followed a more prudent diet than those with only primary school education. Employed men and women had higher BMIs, higher energy intakes but lower plasma fibrinogen levels, and employed women had lower triglyceride levels. No significant differences in total serum cholesterol values were observed. CONCLUSION: These results suggest a drift of CVD risk factors from groups with higher SES to groups with a lower SES from 1996 to 2005, indicating that interventions to prevent CVD should also be targeted at Africans living in rural areas, those with low educational levels, and the unemployed.