Anthropometric indices as measures of body fat assessed by DXA in relation to cardiovascular risk factors in children and adolescents: NHANES 1999-2004.

Objective: Anthropometrics are commonly used indices of total and central adiposity. No study has compared anthropometric measurements to dual-energy X-ray absorptiometry (DXA) measurements as correlates of cardiovascular risks in a nationally representative sample of youth. We aimed to evaluate the validity of anthropometrics compared to DXA-assessed adiposity in relation to cardiovascular risks in youth aged 8-19 years.

Methods: Data were from the National Health and Nutrition Examination Survey 1999-2004 (n=7013). We examined the correlations between anthropometric and DXA measures of adiposity (i.e., body mass index (BMI) versus percent fat mass (%FM) and fat mass index, and waist circumference (WC) and waist-to-height ratio (WHtR) versus percent trunk fat mass (%TFM)) with nine cardiovascular risks, stratified by sex and age, or race-ethnicity.

Results: Anthropometric and DXA adiposity measures were significantly correlated with insulin (r: 0.48 to 0.66), C-reactive protein (r: 0.47 to 0.58), triglycerides (r: 0.15 to 0.41), high-density lipoprotein cholesterol (HDL-C, r: -0.44 to -0.22), systolic blood pressure (SBP, r: 0.10 to 0.31), low-density lipoprotein cholesterol (r: 0.09 to 0.30), total cholesterol (TC, r: 0.01 to 0.29) and glucose (r: 0.05 to 0.20). Only in all youth, BMI was more strongly correlated with SBP (0.22 vs. 0.12, P<0.0001) and HDL-C (-0.34 vs. -0.25, P<0.0001) than %FM; WC but not WHtR was more strongly correlated with HDL-C (-0.37 vs. -0.30, P<0.0001) but less strongly associated with TC (0.12 vs. 0.21, P<0.0001) than %TFM.

Conclusions: DXA adiposity measures do not produce stronger associations with cardiovascular risk factors in youth than BMI or WC.