Prognostic impact of metabolic syndrome by different definitions in a population with high prevalence of obesity and diabetes: the Strong Heart Study.

OBJECTIVE: This study analyzed which definition of the metabolic syndrome is more predictive of cardiovascular events in both diabetic and nondiabetic members of a population-based sample.

RESEARCH DESIGN AND METHODS: A 10-year, longitudinal follow-up of the Strong Heart Study cohort has been evaluated. The analysis included 3,945 participants (2,384 female) with complete data (1,700 with diabetes and 1,468 with arterial hypertension) for evaluation of metabolic syndrome. Those with prevalent cardiovascular disease were excluded (n = 287, of whom 127 were female). Prevalence of metabolic syndrome was assessed based on the World Health Organization (WHO), the National Cholesterol Education Program Adult Treatment Panel (NCEP ATP) III, and International Diabetes Federation (IDF) definitions. The main outcome was 10-year incidence of combined fatal and nonfatal cardiovascular events, including stroke, coronary heart disease, and congestive heart failure.

RESULTS: Fatal and nonfatal cardiovascular events occurred in 1,120 participants. After adjusting for age, sex, and diabetes, metabolic syndrome by all definitions was significantly associated with higher incidence of cardiovascular events (all P < 0.0001). In nondiabetic individuals, incident cardiovascular event rates were about 30-40% higher in those with metabolic syndrome, without a significant difference among definitions (0.03 < P < 0.001), and remained significant in WHO and NCEP ATP III definitions even after further adjustment for obesity, hypertension, and low HDL cholesterol. In the diabetic group, metabolic syndrome risk for cardiovascular events was greatest using the WHO definition (P < 0.002 vs. other models).

CONCLUSIONS: In individuals without diabetes, metabolic syndrome is associated with incident cardiovascular disease, especially with WHO and NCEP ATP III definitions. Metabolic syndrome also predicts higher cardiovascular event rates in diabetic participants, a prediction that is greatest using the WHO definition.