Wednesday, August 15, 2007

The Association of Differing Measures of Overweight and Obesity With Prevalent Atherosclerosis

The Association of Differing Measures of Overweight and Obesity With Prevalent Atherosclerosis

J Am Coll Cardiol, 2007; 50:752-759,

The Dallas Heart Study
Division of Cardiology, Department of Internal Medicine Donald W. Reynolds Cardiovascular Clinical Research Center, the University of Texas Southwestern Medical Center, Dallas, Texas
Manuscript received January 29, 2007; revised manuscript received March 23, 2007, accepted April 1, 2007.

Objectives: This study sought to evaluate the associations between different measures of obesity and prevalent atherosclerosis in a large population-based cohort.

Background: Although obesity is associated with cardiovascular mortality, it is unclear whether this relationship is mediated by increased atherosclerotic burden.

Methods: Using data from the Dallas Heart Study, we assessed the association between gender-specific obesity measures (i.e., body mass index [BMI]; waist circumference [WC]; waist-to-hip ratio [WHR]) and prevalent atherosclerosis defined as coronary artery calcium (CAC) score >10 Agatston units measured by electron-beam computed tomography and detectable aortic plaque measured by magnetic resonance imaging.

Results: In univariable analyses (n = 2,744), CAC prevalence was significantly greater only in the fifth versus first quintile of BMI, whereas it increased stepwise across quintiles of WC and WHR (p trend <0.001 for each). After multivariable adjustment for standard risk factors, prevalent CAC was more frequent in the fifth versus first quintile of WHR (odds ratio 1.91, 95% confidence interval 1.30 to 2.80), whereas no independent positive association was observed for BMI or WC. Similar results were observed for aortic plaque in both univariable and multivariable-adjusted analyses. The c-statistic for discrimination of prevalent CAC was greater for WHR compared with BMI and WC in women and men (p < 0.001 vs. BMI; p < 0.01 vs. WC).
Conclusions: We discovered that WHR was independently associated with prevalent atherosclerosis and provided better discrimination than either BMI or WC. The associations between obesity measurements and atherosclerosis mirror those observed between obesity and cardiovascular mortality, suggesting that obesity contributes to cardiovascular mortality via increased atherosclerotic burden.

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