LMS tables for waist-circumference and waist-height ratio Z-scores in children aged 5-19 y in NHANES III: association with cardio-metabolic risks

BACKGROUND: In adults, anthropometric measures of central adiposity, such as waist-height ratio (WHtR) and waist circumference (WC), are more strongly associated with cardio-metabolic risks than BMI. METHODS: To provide similar quantitative tools for North American children, we created smoothed centile charts and LMS tables for WHtR and WC based on data from the US National Health and Nutrition Survey, cycle III (NHANES III, N = 11,930 aged 2-24 y 1988-1994). RESULTS: Applying these reference charts to subsequent NHANES survey cycles, 1999-2012) demonstrated a significant mean increase in both Z-scores of approximately 0.30 SD. In measuring the strength of the association between anthropometric measures and cardio-metabolic risk factors, a unit change in Z-scores for WHtR, WC, and BMI significantly increased the odds of an adverse outcome in all cases (1.18-2.03, P < 0.0001). Z-scores for both measures of central adiposity were significantly more strongly associated with cardio-metabolic comorbidities than BMI-Z. CONCLUSION: Since Z-scores permit standardized comparisons across ages and genders, they are useful measures of central adiposity in both clinical or research settings. By providing [MS tables for children and adolescents based on North American reference data, we hope to provide quantitative tools for the study of obesity and its complications.