Relevance of intermediate-density lipoprotein cholesterol to Framingham risk score of coronary heart disease in middle-aged men with increased non-HDL cholesterol

Abstract

Cholesterol levels of non-high-density lipoprotein (non-HDL), which contains low-density lipoprotein (LDL), intermediate-density lipoprotein (IDL), very low-density lipoprotein (VLDL) and chylomicron (CM) remnant, have been proven to perform a significant predictor of coronary heart disease (CHD) better than LDL-cholesterol regardless of triglyceride (TG) levels. The present study investigated the relevance of TG-rich lipoproteins (IDL, VLDL, CM) to Framingham risk score (FRS) predictive of 10-year CHD risk. Lipoprotein profiles (cholesterol levels of HDL, LDL, IDL, VLDL, CM) in Japanese men (n = 487) who underwent medical check-up were determined by using our developed anion-exchange high performance liquid chromatography (AEX-HPLC). Total-cholesterol (TC), TG, fasting blood sugar (FBS) and hemoglobin (Hb) A1c were measured by routine methods. The lipoprotein profiles, non-HDL-cholesterol, TC, and TG were examined on these associations with FRS. The lipid levels except for CM-cholesterol were significantly different between two groups (low FRS, < 10%; high FRS, ≥10%) (P < 0.0001), and body mass index (BMI), TC, TG, IDL-, and VLDL-cholesterol were significantly and positively correlated with FRS. Among them, the significant association of non-HDL-cholesterol to FRS was noted (r = 0.411, P < 0.0001). Multiple stepwise regression analysis shows that, in addition to non-HDL-cholesterol, IDL-cholesterol in TG-rich lipoproteins was significantly correlated with FRS in independently of BMI. These correlation results were similarly found even when the part of the study subjects (n = 348) without the drug therapy for hyperlipidemia, diabetes, and hypertension was investigated. These results suggest that IDL-cholesterol may serve as a useful marker for CHD risk in Japanese men with increased non-HDL-cholesterol.