Triglycerides and HDL-cholesterol As Risk Factors for Ischemic Heart Disease. Results from the Québec Cardiovascular Study

The relative importance of reduced plasma high density lipoprotein-cholesterol (HDL-C) levels and elevated plasma triglyceride (TG) concentrations as risk factors for ischemic heart disease (IHD) was examined in a sample of 2177 men from the Québec City suburbs. The sample included 202 men with known IHD. The relationship between HDL-C and TG levels, although significant (r = -0.49, P < 0.0001), was not linear, as most of the variation in HDL-C levels was observed within TG levels below 2.5 mmol/l. Reduced HDL-C (< 0.9 mmol/l) was a prevalent condition in men with IHD (50%) compared to those without IHD (30%). On the other hand 26% and 20% of men with and without IHD, respectively, had elevated TG levels (TG > 2.3 mmol/l). A 2-fold increase in prevalence odds ratio (OR) was observed in men with TG levels > 2.3 mmol/l (95% confidence intervals (CI) [1.2;3.3]). No residual association between elevated TG levels and IHD was found, however, after adjustment for HDL-C concentrations (OR 1.2, 95% CI 0.7;2.1). On the other hand, HDL-C remained a significant predictor of IHD after adjustment for other risk factors (OR 0.3, 95%, CI 0.2;0.6). Men with reduced HDL-C levels were also characterized by a cluster of risk factors such as obesity, diabetes mellitus and hypertension, which may contribute to increase the risk of IHD. Finally, the independent interpretation of cholesterol, TG or LDL-C levels may lead to an inadequate prediction of risk, as a large number of IHD patients showed a cluster of risk factors which included low HDL-C concentrations.