Effects of age, gender, and menopausal status on plasma low density lipoprotein cholesterol and apolipoprotein B levels in the Framingham Offspring Study

Plasma low density lipoprotein (LDL) cholesterol, non-high density lipoprotein (HDL) cholesterol, and apolipoprotein (apo) B, the major protein constituent of LDL, were measured in 1,533 men (mean age 49 +/- 10 years) and 1,597 women (mean age 49 +/- 10 years) participating in the 3rd examination cycle of the Framingham Offspring Study. Mean plasma levels of LDL cholesterol and apoB were higher in men than in women (136 versus 132 mg/dl, P < 0.0001; and 109 versus 95 mg/dl, P < 0.0001, respectively). Increased age was associated with higher plasma LDL cholesterol and apoB levels, especially in women. After adjustment for age and body mass index, LDL cholesterol and apoB levels were still significantly higher in postmenopausal than in premenopausal women, indicating a hormonal effect on LDL metabolism. The associations between coronary heart disease (CHD) and LDL cholesterol, non-HDL cholesterol, apoB, and other plasma lipid and lipoprotein parameters were examined by dividing participants in four groups, based on approximate quartiles for these parameters. Elevated LDL cholesterol levels were not significantly associated with CHD in men, but were in women. This result, at variance with that of several longitudinal studies, is likely due to the cross-sectional design of our analysis. Elevated non-HDL cholesterol and apoB levels were significantly associated with the presence of CHD, in both males and females. A plasma apoB value > or = 125 mg/dl may be associated with an increased risk for CHD. Low plasma levels of HDL cholesterol were also significantly associated with CHD. Plasma triglyceride levels, age and body mass index were strong determinants of LDL cholesterol, non-HDL cholesterol, and apoB levels in men and women. In women, postmenopausal status and elevated blood pressure were also significantly associated with elevated levels of these parameters.