# Predictive performance of the waist-to-height ratio and the conicity index for diagnosing excess body fat in children

## TL;DR

The study found that the waist-to-height ratio is a better predictor of excess body fat in children than the conicity index.

## Contribution

The study provides new cut-off points for the waist-to-height ratio to identify excess body fat in children.

## Key findings

- WHtR had AUC values greater than 0.8, indicating good predictive performance for excess body fat.
- CIndex had AUC values below 0.7, showing poor predictive performance for excess body fat.
- Optimal WHtR cut-off points were 0.47 for boys and 0.45 for girls to identify excess body fat.

## Abstract

To evaluate the performance of waist-to-height ratio (WHtR) and conicity index (CIndex) as predictors of body fat percentage (BF) in children, as well as to determine the most appropriate cut-off points for this population.

This school-based study assessed 314 children aged five to nine years. Body composition was evaluated using bioelectrical impedance analysis (BIA), and children were classified as having excess or normal BF according to sex. WHtR and CIndex were calculated using their respective formulas. To assess the predictive power of CIndex and WHtR, the area under the curve (AUC) of Receiver Operating Characteristic was analyzed, using excess BF by BIA as the gold standard.

WHtR was considered a good predictor of excess BF in both sexes, with AUC values greater than 0.8. CIndex was classified as a poor predictor (AUC<0.7 in both sexes). WHtR showed a significantly higher AUC than CIndex (p<0.001), according to the Wald test. Given the higher accuracy of WHtR, the optimal cut-off points to identify excess BF in children were >0.47 for boys and >0.45 for girls.

WHtR demonstrated good performance in predicting excess BF in the children evaluated and may be included in child health surveillance as an indicator of alterations in body composition.