Recorded presentation

Henry S. Kahn, MD and Yiling J. Cheng, MD, PhD. Division of Diabetes Translation, National Center for Chronic Disease Prevention & Health Promotion, CDC, Mail Stop K-10, 4770 Buford Highway, NE, Atlanta, GA 30341-3717, 770-488-1052, hkahn@cdc.gov

Context: Pediatric assessment by BMI percentiles requires sex-, and age-specification. Previous research suggests that waist-to-height ratio (WHtR), independent of sex or age, might be a superior obesity indicator. Methods: In a cross-sectional, weighted sample representing 58.8 million US youths ages 3-17 years old (NHANES 1999-2000; unweighted N=3,242) we set WHtR thresholds at 0.543 for high risk and 0.498 for moderate risk. These levels yielded similar estimated populations at risk as the BMI thresholds set at the 95^th and 85^th percentiles (sex- and age-specific) by CDC 2000 standards. 54.3 million youths were concordant above or below the high-risk thresholds, leaving 2.3 million with HiWHtR only and 2.2 million with HiBMI only. At moderate-risk levels, the discordant populations included 3.6 million with ModWHtR only and 3.3 million with ModBMI only. For the discordant subpopulations we calculated mean levels of total cholesterol, HDL cholesterol, total/HDL cholesterol, LDL cholesterol, fasting triglycerides, fasting glucose, glycohemoglobin, fasting insulin, C-peptide, HOMA-IR, HOMA-IS, C-reactive protein, homocysteine, systolic and diastolic blood pressures adjusted for sex, age, age², and race-ethnicity. Results: At either risk level, most variables showed no differences (p>0.08) in the discordant groups. Compared to those with HiBMI only, those with HiWHtR only had higher C-reactive protein (0.35 vs 0.19 mg/dL, p=0.051) and subscapular/triceps skinfold ratio (0.88 vs 0.78, p=0.0043). Compared to those with ModBMI only, those with ModWHtR only had lower systolic BP (103.1 vs 110.1 mmHg, p=0.0034). Those with HiWHtR only or ModWHtR only were shorter (by 8 cm) with smaller midthigh circumferences (by 6 cm)(both p<0.0001). Conclusion: The WHtR, while simpler to calculate and interpret, could be equally useful as sex- and age-specific BMI percentiles for identifying youths at metabolic risk.

Learning Objectives:

• …recognize and appreciate the anatomic and physiologic features that distinguish waist-to-height ratio (WHtR) from body mass index (BMI) as markers of weight accumulation;
• …identify previous studies from 3 different continents that have demonstrated equivalence (or superiority) of WHtR compared to BMI as a pediatric assessment tool;
• …define the anatomic landmarks and technique commonly used to measure a child’s waist circumference in the standing position;
• …describe the difficulties in implementing or interpreting the percentiles of body mass index as a sex- and age-specific tool for pediatric risk assessment.

Keywords: Obesity, Child/Adolescent

Presenting author's disclosure statement:
I do not have any significant financial interest/arrangement or affiliation with any organization/institution whose products or services are being discussed in this session.

Recorded presentation