# Development and Application of Children's Sex‐ and Age‐Specific Fat‐Mass and Muscle‐Mass Reference Curves From Dual‐Energy X‐Ray Absorptiometry Data for Predicting Cardiometabolic Risk

## TL;DR

Researchers developed age- and sex-specific body composition reference curves for children to assess cardiometabolic risk based on fat and muscle mass.

## Contribution

The study extends adult-based fat and muscle mass phenotypes to children using DXA data and evaluates their association with cardiometabolic risk.

## Key findings

- HA-HM children showed less favorable HDL, triglycerides, and HOMA-IR compared to LA-HM peers.
- HA-LM children had higher HOMA-IR at baseline and follow-up.
- Phenotypes based on fat and muscle mass may help identify cardiometabolic risk in children.

## Abstract

A dual‐energy x‐ray absorptiometry (DXA)‐derived phenotype classification based on fat mass and muscle mass has been developed for adults. We extended this to a paediatric population.

Children's (≤ 17 years) DXA data in NHANES (n = 6120) were used to generate sex‐ and age‐specific deciles of appendicular skeletal muscle mass index and fat mass index with the Lambda Mu Sigma method. Four phenotypes (high [H] or low [L], adiposity [A] and muscle mass [M]: HA‐HM, HA‐LM, LA‐HM, LA‐LM) were identified based on being above/below the median compared to same‐sex and same‐age peers. These reference curves were applied to the QUALITY cohort (n = 630, 8–10 years of age in 2005) to assess whether the phenotypes correctly identified cardiometabolic risk at baseline, follow‐up (2008–2010), and their longitudinal changes. Multiple linear regression models were adjusted for age, sex, and Tanner's stage.

Compared to the LA‐HM reference group, the HA‐HM phenotype was associated with less favourable HDL, triglycerides, and HOMA‐IR at baseline and first follow‐up, but not in their changes. The HA‐LM phenotype was associated with less favourable HOMA‐IR at baseline and first follow‐up.

Results suggest that phenotypes based on fat and muscle mass may have clinical utility in children and should be further investigated.