Validity of a single-factor model underlying the metabolic syndrome in young adults: confirmatory factor analysis

To determine by confirmatory factor analysis whether a model of the metabolic syndrome including waist circumference-to-height ratio, as a measure of adiposity, has better goodness of fit than that based on waist circumference alone and, on the basis of the data of the best-fit model, to develop an index of global cardiometabolic risk in young adults. Cross-sectional observational study involving 683 university students aged 18 to 30 years, in their first year at the University of Castilla-La Mancha in Spain, during the 2009-10 academic year. We compared the best fit of 2 models of the metabolic syndrome, both of which included the triglyceride-to-high-density lipoprotein cholesterol ratio, HOMA-IR index, and mean arterial blood pressure, but differed in that one of them used waist circumference, whereas the other used the waist circumference-to-height ratio. A metabolic syndrome index (MSI) was constructed and its association with aerobic capacity, daily physical activity and muscle strength was estimated. The single-factor model that included waist circumference was a better indicator of goodness of fit. The MSI was inversely associated with aerobic capacity and muscle strength. This study confirms that a single factor underlies the concept of metabolic syndrome; including the waist circumference-to-height ratio does not result in improvements over the model in which waist circumference alone is considered, and the development of a quantitative MSI may be useful for the quantification of cardiometabolic risk in clinical practice.