Cole, Tim J;
Lobstein, Tim;
(2022)
An improved algorithm to harmonize child overweight and obesity prevalence rates.
Pediatric Obesity
, Article e12970. 10.1111/ijpo.12970.
(In press).
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Abstract
BACKGROUND: Prevalence rates of child overweight and obesity for a group of children vary depending on the BMI reference and cut-off used. Previously we developed an algorithm to convert prevalence rates based on one reference to those based on another. OBJECTIVE: To improve the algorithm by combining information on overweight and obesity prevalence. METHODS: The original algorithm assumed that prevalence according to two different cut-offs A and B differed by a constant amount dz $$ dz $$ on the z-score scale. However the results showed that the z-score difference tended to be greater in the upper tail of the distribution and was better represented by b × dz $$ b\times dz $$ , where b $$ b $$ was a constant that varied by group. The improved algorithm uses paired prevalence rates of overweight and obesity to estimate b $$ b $$ for each group. Prevalence based on cut-off A is then transformed to a z-score, adjusted up or down according to b × dz $$ b\times dz $$ and back-transformed, and this predicts prevalence based on cut-off B. The algorithm's performance was tested on 228 groups of children aged 6-17 years from 20 countries. RESULTS: The revised algorithm performed much better than the original. The standard deviation (SD) of residuals, the difference between observed and predicted prevalence, was 0.8% (n = 2320 comparisons), while the SD of the difference between pairs of the original prevalence rates was 4.3%, meaning that the algorithm explained 96.7% of the baseline variance (88.2% with original algorithm). CONCLUSIONS: The improved algorithm appears to be effective at harmonizing prevalence rates of child overweight and obesity based on different references.
| Type: | Article |
|---|---|
| Title: | An improved algorithm to harmonize child overweight and obesity prevalence rates |
| Location: | England |
| Open access status: | An open access version is available from UCL Discovery |
| DOI: | 10.1111/ijpo.12970 |
| Publisher version: | https://doi.org/10.1111/ijpo.12970 |
| Language: | English |
| Additional information: | © 2022 The Authors. Pediatric Obesity published by John Wiley & Sons Ltd on behalf of World Obesity Federation. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial License (http://creativecommons.org/licenses/by-nc/4.0/). |
| Keywords: | CDC, harmonization, IOTF, obesity, overweight, prevalence, WHO |
| UCL classification: | UCL UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL GOS Institute of Child Health > Population, Policy and Practice Dept UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences > Faculty of Population Health Sciences > UCL GOS Institute of Child Health UCL > Provost and Vice Provost Offices > School of Life and Medical Sciences |
| URI: | https://discovery.ucl.ac.uk/id/eprint/10155184 |
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