Validation of a Measure of Weight-Related Quality of Life in a Community Sample of Normal Weight, Overweight, and Obese 4th and 5th Grade Students

Abstract

The current study extends the quality of life assessment literature by examining the reliability and validity of a disease-specific instrument in a sample of nontreatment-seeking school aged children with overweight and obesity. Participants were 4th and 5th grade students recruited from six Kansas elementary schools. Results of the current study were consistent with the initial evaluation of Sizing Me Up and revealed a five-factor first-order factor structure for the 22-item measure with one second-order factor representing a total score. Consistent with study hypotheses and the available literature, factorial invariance could not be established between a sample of children with healthy weight (n = 168) and the primary sample (n = 134) of children with overweight and obesity. Good evidence for convergent validity within Sizing Me Up factors as well as with similar constructs measured by a general quality of life instrument were revealed. The Sizing Me Up also demonstrated evidence for criterion-related validity with BMI%ile. The current study also advances the quality of life assessment literature by empirically testing the assumption that disease-specific measures assess different constructs than general quality of life measures. Study hypotheses that Sizing Me Up assesses weight-related quality of life constructs were supported. Finally, reliabilities for the five-factor Sizing Me Up factor structure were acceptable for research purposes. However, the scales are unacceptable for clinical use and only the total score should be used with individual children.