The role of HDL cholesterol in metabolic syndrome predicting cardiovascular events. The Gubbio population study

Metabolic syndrome (MS) has recently been claimed to be an important new risk factor for the occurrence of coronary heart disease (CHD) and cardiovascular disease (CVD) events, although it is simply a combination of known risk factors used in a dichotomized fashion. The aims of this analysis were to explore the predictive role of MS for CHD and CVD events in a population study, in comparison with using the same factors in a continuous fashion, with special emphasis on HDL cholesterol.

In the second examination of the Gubbio population study from central Italy, 2650 cardiovascular disease-free men and women, aged 35-74 years around 1990, were examined and followed-up for 12 years. The classic risk factors (sex, age, systolic blood pressure, serum cholesterol and smoking habits) were studied as predictors of CHD and CVD events, alone and with the contribution of other factors (HDL cholesterol, blood glucose, serum triglycerides and waist circumference) included in the so-called MS, based on several multivariate models. MS was also tested after adjustment for other risk factors. MS produced a predictive significant relative risk of 1.67 for CHD events and 1.82 for CVD events, but considering its single risk factors, the only ones contributing to prediction were HDL cholesterol and systolic blood pressure. Dedicated analyses showed that MS does not add anything to the power of prediction beyond the role of the single risk factors treated in a continuous fashion, while the best predictive power is obtained using classic risk factors (sex, age, smoking habits, total cholesterol, systolic blood pressure) with the addition of HDL cholesterol.

The predictive power of MS is bound only to the presence of HDL cholesterol and blood pressure and does not add anything to using the same risk factor treated in a continuous fashion.