Comparability of skinfold thickness to DXA whole-body total fat in their associations with serum triglycerides in youths

OBJECTIVE: To determine the comparability of triceps and subscapular skinfold thicknesses with dual X-ray absorptiometry (DXA) whole-body total fat (kg) in relation to serum triglyceride (TG) levels and increased risk of elevated TG levels, and identified optimum skinfold cutoffs for screening purposes in US adolescents. SUBJECTS/METHODS: Data from triceps and subscapular skinfold thickness, DXA whole-body total fat and serum TGs were obtained from 1505 US adolescents ages 12.00-17.99 years, who participated in two continuous National Health and Nutrition Examination Survey (NHANES) cycles 2001-2004. Study associations were examined with linear and logistic models, and ROC (receiver operating characteristic) analyses were used to derive skinfold cutoffs for identifying the risk of elevated TG levels. RESULTS: Using area under the curves (AUCs) as metrics of prediction accuracy (with bootstrapped 95% CIs), no significant differences were found between skinfolds and DXA logistic models for predicting elevated TG levels. Similarly, skinfold and DXA models had comparable precision in predicting continuous serum TG from bootstrapped root mean squared errors for both sexes. Population-adjusted marginal mean estimates indicated that youths whose skinfolds are in the top quartile had TG levels within 83-108 mg/dl. Skinfold cutoffs for predicting elevated estimated TG using ROC analyses showed that cutoffs decreased with age and ranged from 13 to 30 mm for ages 12-17, in yearly intervals. CONCLUSION: Skinfold thicknesses were comparable to DXA whole-body total fat in predicting serum TG levels. These skinfold cutoffs could be used in practical settings as a first pass screener for identifying US adolescents at risk of elevated serum TGs.