Metabolic syndrome: Controlling the epidemic

The metabolic syndrome is a cluster of risk factors associated with cardiovascular disease. Presently, there is an epidemic of this syndrome and obesity in the United States and worldwide. While there are various definitions of the syndrome, the National Cholesterol Education Program Adult Treatment Panel III has created a practical definition that can be easily implemented in clinical practice. It requires three of the following criteria: central obesity, hypertriglyceridemia, low high-density lipoprotein cholesterol, high blood pressure, and high fasting glucose.

Data from the Third National Health and Nutrition Examination Survey (NHANES III), conducted in the United States from 1988 to 1994, demonstrated that the metabolic syndrome was present in almost 23% of men and women.1 The prevalence varied with older age and ethnic status. It was present in 4.6%, 22.4%, and 59.6% of normal weight, overweight, and obese men, respectively, with similar values in women.

The Diabetes Epidemiology: Collaborative Analysis of Diagnostic Criteria in Europe (DECODE) study group found a 15% overall prevalence of the metabolic syndrome in nondiabetic European men and women.2 Its presence was associated with a 1.4-fold increase in all-cause mortality for both men and women, with a 2.3-fold increase in the risk of cardiovascular disease mortality for men and a 2.8-fold increase for women.

The Botnia study evaluated the prevalence of cardiovascular morbidity and mortality associated with the metabolic syndrome in a high-risk insulin-resistant and/or diabetic Scandinavian population.3 In men and women, respectively, the metabolic syndrome was found in 15% and 10% of subjects with normal glucose tolerance, 64% and 42% of those with impaired fasting glucose or impaired glucose tolerance, and 84% and 78% of those with type 2 diabetes. The risk for coronary heart disease and stroke was increased threefold in subjects with the metabolic syndrome. Cardiovascular mortality was 12% over a median follow-up of 6.9 years compared with 2.2% in those without metabolic syndrome.

Ninomiya and Criqui (page 27) report on the association of the metabolic syndrome with myocardial infarction (MI) and stroke in a nondiabetic population using the NHANES III database. After adjusting for age, sex, ethnicity, and smoking status, patients with metabolic syndrome had a twofold increase in the risk of MI or stroke. These data support the concept that the metabolic syndrome defines a cohort that is at increased risk for vascular disease morbidity and mortality.

Conclusion

Physicians and patients must be educated about the metabolic syndrome so that high-risk individuals can be identified. An integrated approach to management can then be undertaken. Implementing preventive lifestyle interventions, such as diet modification, increased physical activity, weight management, and smoking cessation, is imper-ative. Some subjects may require pharmacologic intervention.