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

Background 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. Methods 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 (WHtR SDS ) <1 or ≥1 at 5 years. Student’s t -tests and Chi-squared tests were used in the analyses. Results Association between BMI SDS and WHtR SDS at 5 years showed that 55% of children with WHtR SDS ≥1 at 5 years had normal BMI SDS ( p < 0.001). Children with WHtR SDS ≥1 at 5 years had from an early age significantly higher mean BMI SDS and WHtR SDS than children with values <1. Conclusions BMI classification misses every second child with WHtR SDS ≥1 at 5 years, suggesting that WHtR adds value in identifying children with abdominal adiposity who may need further investigation regarding cardiometabolic risk factors.