A Single Factor Underlies the Metabolic Syndrome
A confirmatory factor analysis
- Manel Pladevall, MD, MS123,
- Bonita Singal, MD, PHD4,
- L. Keoki Williams, MD, MPH1,
- Carlos Brotons, MD, PHD5,
- Heidi Guyer, MPH26,
- Josep Sadurni, MD2,
- Carles Falces, MD2,
- Manuel Serrano-Rios, MD, PHD7,
- Rafael Gabriel, MD, PHD8,
- Jonathan E. Shaw, MD, FRACP9,
- Paul Z. Zimmet, MD, PHD9 and
- Steven Haffner, MD, MPH10
- 1Henry Ford Health System, Center for Health Services Research, Detroit, Michigan
- 2Hospital General de Vic, Cardiology Department, Vic, Barcelona, Spain
- 3Programa de Doctorat, Departament de Medicina Interna, Universitat Autònoma de Barcelona, Bellaterrra, Barcelona, Spain
- 4University of Michigan, Department of Emergency Medicine, Ann Arbor, Michigan
- 5Equip d’Atenció Primària Sardenya, Barcelona, Barcelona, Spain
- 6University of Michigan, Institute for Social Research, Ann Arbor, Michigan
- 7Hospital Clínico San Carlos, Internal Medicine Department, Madrid, Madrid, Spain
- 8Hospital Universitario La Paz, Clinical Epidemiology Department, Madrid, Madrid, Spain
- 9International Diabetes Institute, Caulfield, Victoria, Australia
- 10University of Texas Health Science Center, San Antonio, Texas
- Address correspondence and reprint requests to Manel Pladevall, Center for Health Services Research, Henry Ford Health System, One Ford Place, Suite 3A, Detroit, MI 48202. E-mail: mpladev1{at}hfhs.org
Abstract
OBJECTIVE—Confirmatory factor analysis (CFA) was used to test the hypothesis that the components of the metabolic syndrome are manifestations of a single common factor.
RESEARCH DESIGN AND METHODS—Three different datasets were used to test and validate the model. The Spanish and Mauritian studies included 207 men and 203 women and 1,411 men and 1,650 women, respectively. A third analytical dataset including 847 men was obtained from a previously published CFA of a U.S. population. The one-factor model included the metabolic syndrome core components (central obesity, insulin resistance, blood pressure, and lipid measurements). We also tested an expanded one-factor model that included uric acid and leptin levels. Finally, we used CFA to compare the goodness of fit of one-factor models with the fit of two previously published four-factor models.
RESULTS—The simplest one-factor model showed the best goodness-of-fit indexes (comparative fit index 1, root mean-square error of approximation 0.00). Comparisons of one-factor with four-factor models in the three datasets favored the one-factor model structure. The selection of variables to represent the different metabolic syndrome components and model specification explained why previous exploratory and confirmatory factor analysis, respectively, failed to identify a single factor for the metabolic syndrome.
CONCLUSIONS—These analyses support the current clinical definition of the metabolic syndrome, as well as the existence of a single factor that links all of the core components.
- AIC, Akaike information criterion
- CFA, confirmatory factor analysis
- CVD, cardiovascular disease
- EFA, exploratory factor analysis
- HOMA-IR, homestasis model assessment of insulin resistance
- MAP, mean arterial pressure
Footnotes
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Additional information for this article can be found in an online appendix at http://care.diabetesjournals.org.
A table elsewhere in this issue shows conventional and Système International (SI) units and conversion factors for many substances.
The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore be hereby marked “advertisement” in accordance with 18 U.S.C Section 1734 solely to indicate this fact.
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- Accepted September 20, 2005.
- Received May 12, 2005.
- DIABETES CARE
