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DOI: 10.3390/children8040303; PMCID: PMC8071434


Extreme body mass index (BMI) values (i.e., above the 97th and below the 3rd percentiles) are inaccurately represented on the Centers for Disease Control and Prevention's growth curves, which may limit the utility of BMI percentile and BMI z-score for capturing changes in clinical outcomes for patients at extreme weights. Modeling child obesity severity based upon the percentage of BMI in excess of the 95th percentile (BMI95pct) has been proposed as an improved metric to better capture variability in weight at extreme ends of growth curves, which may improve our understanding of relationships between weight status and changes in clinical outcomes. However, few studies have evaluated whether the use of BMI95pct would refine our understanding of differences in clinical psychosocial constructs compared to previous methods for categorization. This cross-sectional study evaluated child obesity severity based on BMI95pct to examine potential group differences in a validated, obesity-specific measure of Health-Related Quality of Life (HRQoL). Four hundred and sixty-five children with obesity completed Sizing Me Up, a self-report measure of HRQoL. Children were classified into categories based on BMI95pct (i.e., class I: ≥ 100% and < 120%; class II: ≥ 120% and < 140%; class III: ≥ 140%). The results indicate that children with class III obesity reported lower HRQoL than children with class I and class II obesity; however, there were no differences between Class II and Class I. In much of the previous literature, children with class II and class III obesity are often combined under the category "Severe Obesity" based upon BMI above the 99th percentile. This study suggests that grouping children from various classes together would neglect to capture critical differences in HRQoL. Future research including children with severe obesity should consider obesity classes to best account for functioning and clinical outcomes.

Journal Title

Children (Basel)





First Page



BMI percentage; child obesity; health-related quality of life; obesity category; obesity class


This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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