The differential association between various anthropometric indices of obesity and subclinical atherosclerosis

BACKGROUND: Recent observational studies have reported differential quantitative relationships between the different anthropometric indices of obesity and risk for cardiovascular (CV) events. Specifically, waist circumference and waist-to-hip ratio (WHR) as crude measures of abdominal obesity were shown to be more predictive of CV events than body mass index (BMI). However, it remains undetermined whether indices of abdominal obesity are also more strongly associated with early subclinical atherosclerosis in asymptomatic individuals. METHODS: The associations between carotid intimal-medial thickness (cIMT) as a validated marker of subclinical atherosclerosis and each of BMI, waist circumference and WHR were compared among 1578 middle-aged men free of clinical CV disease enrolled in the Fire Fighter and Their Endothelium (FATE) study. RESULTS: In univariate analyses, the correlation with cIMT as well as the ability to predict substantially increased atherosclerotic burden (cIMT>75% percentile of the cohort) was strongest for WHR, intermediate for waist circumference, and weakest for BMI (Pearson's coefficient of 0.21, 0.18 and 0.12, respectively; area under the receiver operating characteristics curve [AUC] of 0.65, 0.62 and 0.58, respectively, P<0.01 for differences). Within each traditional BMI category, WHR uniformly outperformed waist circumference in further refining discrimination for increased atherosclerotic burden. In multivariable analyses, WHR consistently demonstrated the strongest graded independent relationship with cIMT, beyond most of the established risk factors of atherosclerosis, and superseded both waist circumference and BMI. CONCLUSION: Our findings support the use of WHR for estimating adiposity-related atherosclerotic burden in clinical practice and in obesity research. Moreover, our study suggests that the increased CV risk associated with abdominal obesity may be mediated in part by the increased anatomic extent of atherosclerotic vascular disease.