Predicting cardiovascular risk in patients with metabolic syndrome depends on definition used for the syndrome
Research Activities, September 2010, No. 361
Metabolic syndrome is characterized by problems such as increased blood pressure, elevated insulin levels, excess fat around the waist, and abnormal cholesterol levels. It is often a precursor for diabetes and can increase a person's risk of cardiovascular diseases such as heart attack and stroke. Physicians can use two different classification systems to determine if someone has metabolic syndrome. However, a new study finds that each definition differs in its ability to predict a person's cardiovascular risk.
Researchers focused their attention on two classification systems. One, the National Cholesterol Education Program Adult Treatment Panel (ATP) III criteria, is the most widely used in the United States. Patients must meet any three of the following criteria: elevated waist circumference (>40 in. in men or >35 in. in women); elevated triglycerides; decreased high density lipoprotein-cholesterol, the so-called "good cholesterol;" elevated blood pressure; or elevated blood sugar levels. To meet criteria for the other system created by the International Diabetes Federation (IDF), individuals have to have an elevated waist circumference (>37 in. in men or 31.5 in. in women) and two of the other four ATP-III criteria.
A total of 22,719 individuals in the Reasons for Geographic and Racial Differences in Stroke study were evaluated. Half were black and half were women. Nearly half were found to have metabolic syndrome (47 percent). Of those with the condition, 79 percent met both definitions, 6 percent met the criteria based only on ATP criteria, and 14 percent met IDF criteria only. Individuals defined by ATP criteria had the highest odds of current cardiovascular disease and future risk, as measured by Framingham risk scores, compared with study participants without metabolic syndrome. Individuals with metabolic syndrome only defined by IDF had 43 percent higher odds of cardiovascular disease and a twofold increased odds of future risk. The study was supported in part by the Agency for Healthcare Research and Quality (HS13852).
See "Variations in prevalent cardiovascular disease and future risk by metabolic syndrome classification in the Reasons for Geographic and Racial Differences in Stroke (REGARDS) study," by Todd M. Brown, M.D., M.P.H., Jenifer H. Voeks, Ph.D., Vera Bittner, M.D., M.S.P.H., and Monika M. Safford, M.D., in the March 2010 American Heart Journal 159, pp. 385-391.