Body mass index classification misses to identify children with an elevated waist-to-height ratio at 5 years of age

Abdominal adiposity is an important risk factor in the metabolic syndrome. Since BMI does not reveal fat distribution, waist-to-height ratio (WHtR) has been suggested as a better measure of abdominal adiposity in children, but only a few studies cover the preschool population. The aim of the present study was to examine BMI and WHtR growth patterns and their association regarding their ability to identify children with an elevated WHtR at 5 years of age. A population-based longitudinal birth cohort study of 1540 children, followed from 0 to 5 years with nine measurement points. The children were classified as having WHtR standard deviation scores (WHtRSDS) <1 or ≥1 at 5 years. Student’s t-tests and Chi-squared tests were used in the analyses. Association between BMISDS and WHtRSDS at 5 years showed that 55% of children with WHtRSDS ≥1 at 5 years had normal BMISDS (p < 0.001). Children with WHtRSDS ≥1 at 5 years had from an early age significantly higher mean BMISDS and WHtRSDS than children with values <1. BMI classification misses every second child with WHtRSDS ≥1 at 5 years, suggesting that WHtR adds value in identifying children with abdominal adiposity who may need further investigation regarding cardiometabolic risk factors.