Is utility-based quality of life associated with overweight in children? Evidence from the UK WAVES randomised controlled study.

BACKGROUND: Quality-Adjusted Life Years (QALYs) are often used to make judgements about the relative cost-effectiveness of competing interventions and require an understanding of the relationship between health and health-related quality of life (HRQOL) when measured in utility terms. There is a dearth of information in the literature concerning how childhood overweight is associated with quality of life when this is measured using utilities. This study explores how weight is associated with utility-based HRQOL in 5-6 year olds and examines the psychometric properties of a newly developed pediatric utility measure - the CHU9D instrument. METHODS: Weight and HRQOL were examined using data collected from 1334 children recruited within a UK randomised controlled trial (WAVES) (ISRCTN97000586). Utility-based HRQOL was measured using the CHU9D, and general HRQOL measured using the PedsQL instrument. The association between weight and HRQOL was examined through a series of descriptive and multivariate analysis. The construct validity of the CHU9D was further assessed in relation to weight status, in direct comparison to the PedsQL instrument. RESULTS: The HRQOL of children who were either overweight or obese was not statistically different from children who were healthy or underweight. This result was the same for when HRQOL was measured in utility terms using the CHU9D instrument, and in general terms using the PedsQL instrument. Furthermore, the results support the construct validity of the newly developed CHU9D as the PedsQL total HRQOL scores corresponded well with the individual CHU9D dimensions. CONCLUSION: At age 5-6 years, the inverse association between overweight and HRQOL is not being captured by either the utility-based CHU9D instrument nor the PedsQL instrument. This result has implications for how the cost-effectiveness of childhood obesity interventions is measured in children aged 5-6 years. TRIAL REGISTRATION: ISRCTN Registry: ISRCTN97000586 19(th) May 2010.