Akey question in the debate concerning the metabolic syndrome (1,2) is whether the risk accompanying it is more than the sum of its parts. Grundy (1) asserts that “risk factors are multiplicative, i.e., risk for ASCVD [atherosclerotic cardiovascular disease] from risk factors rises geometrically, not linearly, as the number of risk factors increases. Therefore, total risk is more than a summation of the individual factors.” The study by Yusuf et al. (3) is offered to support this statement, but this study is a standardized case-control study of 27,098 participants in 52 countries representing several major ethnic groups to assess the relation between BMI, waist and hip circumferences, and waist-to-hip ratio to myocardial infarction overall and for each group. The metabolic syndrome is not even mentioned in the article.
In the same issue of Diabetes Care, Sunderström et al. (4) published a study evaluating the risk factors for cardiovascular death in >2,000 individuals followed for 30 years after being studied at age 50. More than 1,000 of them were reexamined at age 70 and followed for 9 more years. Sunderström et al. showed that the “metabolic syndrome did not predict cardiovascular mortality independently of its individual components at any age” and concluded that “the metabolic syndrome might be viewed as a clinically handy summary measure of nontraditional risk factors rather than as a strong biological entity.” Thus, this evidence suggests that the answer to the key question posed above is that the risk of the metabolic syndrome for cardiovascular events is no more than the sum of its parts. Whether the metabolic syndrome serves an important function to alert physicians and patients of the importance of addressing these risk factors is a separate issue.