Aims: Recent studies suggested that subclasses of high-density lipoprotein (HDL) may be a better biomarker to predict the risk of atherosclerotic disorders. We aimed to examine the association of HDL2- and HDL3-cholesterol (HDL2-C and HDL3-C) with carotid intima-media thickness (IMT) using a new method to quantify the HDL-C subclasses.
Methods: Participants were 657 Japanese subjects (434 women) who received a health examination (mean age: 73 years). Serum samples were analyzed by the homogenous assay for HDL-C and HDL3-C. HDL2-C was calculated indirectly by subtracting HDL3-C from HDL-C. HDL3-C measured by this assay was well correlated with that measured by ultracentrifugation (r=0.898, p＜0.001). The maximum IMT (max-IMT) and plaque score (PS) were evaluated by ultrasonography following the standard protocol.
Results: HDL3-C was associated with age both in men (r=－0.322, p＜0.0001) and women (r=－0.315, p＜0.0001). In a simple regression analysis, max-IMT showed an inverse association with HDL3-C, whereas no significant association was observed with HDL2-C. A multiple linear regression analysis indicated, however, that the association between HDL3-C and max-IMT was not significant in both aged and younger populations when age was included in the analysis. Further, not only HDL2-C but also HDL3-C was not a significant predictor of 'atherosclerotic arteries' defined as the max-IMT ≥1.5 mm. Similar results were observed in the analysis on PS.
Conclusions: Neither HDL3-C nor HDL2-C was significantly associated with carotid atherosclerosis in the Japanese population in this study.
Keywords: Atherosclerosis; Cholesterol; High-density lipoprotein (HDL); Intima-media thickness (IMT).