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Weight-for-height in children aged 4-12 years. A new index compared to the normalized body mass index
S Chinn1, R J Rona, M C Gulliford
1Department Public Health Medicine, United Medical School, Guy's Hospital, London, UK.
Insights
A new weight-for-height index, (weight -9)/height3.7, shows similar correlation to skinfold thickness as BMI in children aged 4-12. This new index offers stable variance, simplifying analysis compared to BMI.
Area of Science:
- Pediatric Nutrition
- Anthropometry
- Growth Monitoring
Background:
- Accurate assessment of weight-for-height in children is crucial for monitoring growth and nutritional status.
- Existing indices like Body Mass Index (BMI) may require complex transformations for analysis in pediatric populations.
- The National Study of Health and Growth provides valuable data for evaluating anthropometric indices.
Purpose of the Study:
- To develop and validate a new weight-for-height index for children.
- To compare the performance of the new index with the Body Mass Index (BMI) in relation to skinfold thickness.
- To assess the suitability of anthropometric indices for cross-ethnic comparisons.
Main Methods:
- Utilized data from 3357 white English boys and 3050 white English girls (ages 4-12) from the 1990 National Study of Health and Growth.
- Developed a new index: (weight in kg - 9) / height (in m)^3.7, based on prediction of triceps + subscapular skinfold thickness.
- Evaluated the new index's correlation with normalized skinfold thickness and compared its variance stability with BMI.
Main Results:
- The new weight-for-height index demonstrated a correlation with normalized skinfold thickness comparable to BMI in children aged 4-12 years.
- The new index exhibited stable variance across ages 4-12 after log transformation, unlike BMI which required age-related parameter adjustments.
- Neither index proved effective for comparing skinfold measurements across ethnic groups; Gujarati children were thinner than white children, while Afro-Caribbean children showed mixed results.
Conclusions:
- The proposed weight-for-height index offers a simpler alternative to BMI for assessing children aged 4-12, with more stable variance properties.
- Further research is needed to refine anthropometric indices for accurate cross-ethnic comparisons in child populations.
- Centiles for the new weight-for-height index and BMI were calculated for white English boys and girls aged 4-12 years.
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.