Metabolic syndrome, its preeminent clusters, incident coronary heart disease and all-cause mortality - Results of prospective analysis for the Atherosclerosis Risk in Communities study

Objective. To investigate the prospective association between Metabolic Syndrome (MetS) and coronary heart disease (CHD) and all-cause mortality. Subjects and Design. A bi-racial cohort of 14 699 middle-aged Americans from the Atherosclerosis Risk in Communities study were followed for the development of new CHD and death over a period of 9 years. MetS, using the original ATP-III criteria, was defined as having at least three of the following components: elevated blood pressure (BP), elevated plasma glucose, elevated blood triglyceride (TG), increased waist circumference, and low HDL cholesterol (HDL-c). Incident CHD cases included hospitalized myocardial infarction (MI), fatal CHD, revascularization procedures, and silent MI as detected by EKG. Results. The prevalence of the MetS at baseline was 29%, 30%, 40% and 26% among CHD-free white women, white men, black women, and black men, respectively. There were 1018 incident CHD cases and 1039 deaths. The relative risk (RR) and 95% confidence interval (CI) of incident CHD associated with MetS was 2.46 (1.99, 3.03) for women and 1.86 (1.59, 2.18) for men. Clear dose-response relationship between the number of MetS components and incidence of CHD was found (P for linear trend <0.001). The following three clusters of MetS components posed the highest risk for CHD: (i) the elevated BP and glucose and low HDL-c group [RR = 5.68 (3.44, 9.37)]; (ii) the elevated BP and glucose and TG group [RR = 5.08 (2.96, 8.70)]; and (iii) the elevated BP and TG and low HDL-c group [RR = 3.98 (2.75, 5.77)]. When all five components co-existed, the risk was the highest [RR = 6.24 (4.65, 8.36)]. Similar results with attenuated RR were found for all-cause mortality. Conclusions. Individuals, especially women, with the MetS have significantly higher risk of developing CHD. The riskiest combination is high-BP and glucose clustered with low HDL-c or high TG. These data highlight the importance of targeting MetS in the prevention of CHD and premature death.