Abstract
BACKGROUND: The evaluation of children with cerebral palsy (CP) focuses on activity level measurement to examine the effect of health-care interventions on their physical functioning in the home, school, and community settings. This study aimed to identify the psychometric properties of the Korean version of the Childhood Health Assessment Questionnaire (CHAQ) by applying the Rasch model. The use of the Rasch model has an advantage in that item characteristic curve estimation is not affected by the characteristics of subject groups. METHODS: Data were collected from 65 children with CP aged 75-190 months using the Korean version of the CHAQ. Response data were analyzed according to the Rasch model, and item fitness and difficulty and the appropriateness and reliability of the rating scale were evaluated. RESULTS: Among the 30 items of the Korean version of the CHAQ, two items (nail-cutting and opening a bottle cap that was already opened) were shown to be misfit items with low fitness. The analysis results for item difficulty indicated the requirement for modification of item difficulty, pointing out the need for the addition of question items with both higher and lower difficulty. The use of 4-point rating scale in the evaluation questionnaire was shown to be appropriate. With respect to analysis outcomes, the subjects' separation reliability value and separation index were 0.97 and 5.92, respectively. In contrast, the separation reliability value and separation index for the question items were 0.95 and 4.51, respectively. CONCLUSIONS: The results of this study suggest the need for the modification of item fitness and difficulty. The psychometric properties of the Korean version of the CHAQ were identified using the item response theory-based Rasch analysis.