Apo CIII Levels in Turkish Adults: Association with coronary risk and metabolic syndrome

Since apolipoprotein C-III (apoC-III) has been proposed to indicate coronary risk in healthy subjects, we studied cross-sectionally in a population sample representative of Turkish adults whether serum levels of total apoC-III or its components were independent markers of prevalent coronary heart disease (CHD) or were related to the metabolic syndrome (MS). In 857 unselected participants of the Turkish Adult Risk Factor Survey in 2001, apoC-III and other risk variables were evaluated. CHD was diagnosed on the basis of clinical findings and Minnesota coding of resting ECGs. The sample consisted of middle-aged and elderly adults, 42% of whom had MS identified by criteria of the ATP III. ApoC-III values were measured by turbidimetric immunoassay. Mean concentrations for nonHDL apoC-III in men and women were 6.4 and 6.2 mg/dl, respectively, and for apoC-III in HDL were 6.2 and 6.3 mg/dl, respectively. Both fractions of apoC-III were significantly correlated with lipids, lipoproteins, apo B, anthropometric measures and blood pressures in both sexes. Correlations of both were high with serum triglycerides (rs = around 0.70) and apo B (rp = around 0.37). Total apoC-III as well as both fractions were significantly correlated in women also with C-reactive protein (rs = around 0.20, p<0.001). High (>7.0 mg/dl) as opposed to lower levels of nonHDL apoC-III indicated the presence of hypertriglyceridemic hyperapo B with an age-adjusted OR of 13.8; it indicated the presence of metabolic syndrome with 4.66-fold likelihood. Total apoC-III and nonHDL apoC-III proved to be significantly (p trend <0.05 and 0.002) and strongly associated with prevalent CHD in men even when adjusted for age, LDL- and HDL-cholesterol; namely, the OR across upper and lower quartiles was 3.9 (CI 1.3;11.4), and 8.8-fold (CI 2.6;29.8), respectively. We concluded that total and nonHDL apoC-III are each a determinant in Turkish men and women of the metabolic syndrome and of hypertriglyceridemic hyperapoB. They are also significant markers of prevalent CHD in men independent of LDL- and HDL-cholesterol levels.