Apolipoprotein B levels and related factors in a rural white South African community--the CORIS study. Coronary Risk Factor Study.

OBJECTIVE

In a survey of the Coronary Risk Factor Study (CORIS), apolipoprotein B (apoB) levels were determined to ascertain their impact on coronary heart disease (CHD) risk. Other CHD risk factors associated with apoB were also identified.

DESIGN

Cross-sectional analytical study, which included CHD risk factor and dietary questionnaires, electrocardiography, anthropometric and blood pressure measurements, and a blood sample for a lipid profile.

SETTING AND PARTICIPANTS

The three districts of Riversdale, Robertson and Swellendam in the south-western Cape; a 25% random sample of 1,528 white respondents aged 15-68 years.

RESULTS

Men tended to have higher mean apoB levels than women. Classification of CHD risk by apoB levels and total cholesterol (TC) levels did not correspond, as only 61% of men and 58.5% of women were classified in the same risk categories. Respondents in the highest apoB risk category reported a medical history of hypercholesterolaemia and hypertension more frequently than those in lower categories. There was a significant increase from the low to the high apoB risk category of TC, low-density lipoprotein (LDL) cholesterol, triglyceride levels, body mass index and percentage body fat. Using stepwise multiple regression, 84.9% of the variation in apoB of men and 85.8% in apoB of women were accounted for by significantly associated variables.

CONCLUSION

Although apoB may be a better predictor of CHD than TC or LDL cholesterol concentrations, its easy approximation with the formula (TC-HDLC)/2 + 20, high cost, measurement variability and an approach in management similar to that for raised TC discourage its routine use in the screening of patients for CHD.