Weight-for-height in children aged 4-12 years. A new index compared to the normalized body mass index

Abstract

Data from the 1990 survey of the National Study of Health and Growth, comprising 3357 white English boys and 3050 white English girls, were used to construct and evaluate a new index of weight-for-height. Prediction of triceps + subscapular skinfold thickness, using half of the data, led to the index (weight -9)/height3.7, where weight was in kilograms, height in metres. Using the second half of the data the index was shown to have almost as good a correlation with normalized (triceps + subscapular skinfold) as the body mass index (BMI) in children aged 4-12 years. The new weight-for-height index had stable variance from age 4 to 12 years after simple log transformation, unlike the BMI which required transformation via three age-related parameters prior to analysis or centile calculation. Neither index was a good proxy for skinfold measurements for comparison of ethnic groups. From data from inner city areas surveyed in 1989 children of Indian subcontinent origin had substantially lower weight-for-height, but only Gujarati children were thinner than white children, whereas Afro-Caribbean children were slightly heavier for their height, but thinner. Centiles of weight-for-height, and of BMI by age, for ages 4-12 years, were calculated for white English boys and white English girls.