The IWQOL-Kids(©): establishing minimal clinically important difference scores and test-retest reliability.

This study presents additional psychometric testing of the Impact of Weight on Quality of Life-Kids (IWQOL-Kids) with aims to establish distribution-based minimal clinically important difference scores (MCIDs) and evaluate test-retest reliability. Participants (N=263) represent a pooled sample of treatment-seeking obese adolescents (aged 11-19 years) from four large studies examining health-related quality of life (HRQOL) and psychosocial outcomes (Mz(BMI)=2.6 ± 0.4; M(age)=15.1 ± 1.9; 64% female; 51% Black, 46% White). Adolescents completed the IWQOL-Kids©. Standard errors of measurement, which represent the MCID for each scale, were: Physical Comfort=8.8; Body Esteem=7.7; Social Life=8.1; Family Relations=6.2; Total QOL =4.8. Test-retest reliabilities ranged from 0.75-0.88. These data provide further support for the excellent psychometric properties of the IWQOL-Kids. In addition, preliminary MCIDs for IWQOL-Kids scales have now been established, which can be used in clinical trials.