Body composition and BMI growth charts in children with down syndrome

Background and Objectives: New US Down syndrome (DS) BMI growth charts were recently published, but their utility in identifying children with excess adiposity or increased cardiometabolic risk (CMR) remains unknown. We sought to compare the ability of the Centers for Disease Control and Prevention (CDC) BMI 85th percentile and DS-specific BMI 85th percentile to identify excess adiposity in children with DS. METHODS: Participants with DS aged 10 to 20 years were enrolled in a cross-sectional CMR study. Data from typically developing children enrolled in the Bone Mineral Density in Childhood Study (BMDCS) were used for comparison. Sensitivity and specificity were calculated to assess the CDC BMI 85th percentile in the BMDCS and DS groups, and the DS-specific BMI 85th percentile in the DS group, relative to fat mass index (FMI) ≥80th percentile, a threshold associated with increased CMR. RESULTS: Included were 121 DS participants (age 14.8 ± 3.3 years, 57% girls) and 7978 BMDCS reference data points (age 15.0 ± 3.0 years, 51.3% girls). The CDC BMI 85th percentile identified FMI ≥80th percentile with 96.9% sensitivity and 87.4% specificity in typically developing children. Similarly, the CDC BMI 85th percentile identified FMI ≥80th percentile with 100% sensitivity and 78.3% specificity in children with DS. In contrast, the sensitivity of the DS-specific BMI 85th percentile was only 62.3% (P <.0001), but was 100% specific. CONCLUSIONS: For children with DS ≥10 years, the CDC BMI growth chart 85th percentile is a better indicator of excess adiposity, than the new DS-specific BMI charts. Additional studies are needed to clarify the relationships of BMI and FMI with CMR in DS.