Background The Childhood Health Assessment Questionnaire (CHAQ) is widely used to measure functional impairment in children with juvenile idiopathic arthritis (JIA) (1). However, the original version (CHAQ30) has reduced overall validity in terms of an increasing ceiling effect and a decreasing discriminative ability due to considerable improvements in functional ability of JIA-children (2).
Objectives The aim of this study was to evaluate and validate a revised version including eight physically demanding questions (CHAQ38) with a new categorical response model (CAT2) (3) and a simplified scoring of the original response model (CAT1) (4) in a Danish population of JIA-children and an age- and gender-matched group of healthy controls.
Methods 68 patients and 118 controls aged 10-16 years filled in the CHAQ30 with eight new items (CHAQ38) and two response models (CAT1 and CAT2). Demographic data in both groups and disease-specific data among patients was obtained. Statistical analysis of the four revisions was done to evaluate score distribution and test the ability to distinguish between patients and controls and among patients, and avoid a ceiling effect.
Results All versions had scores close to zero in both groups (median/mean values in patients: -0.0789-0.1053/-0.1602-0.1896. In controls: 0/0.0215-0.1024), indicating only mild disease in patients. Nevertheless, all versions equally distinguished between patients and controls (p<0.001) and between patients with or without active disease (p≤0.008). In both groups all versions suffered from a ceiling effect (% at ceiling in patients: 16.2-33.8. In controls: 39.6-75.4) and deviated significantly from a normal distribution (Kolmogorov-Smirnov values in patients: 0.176-0.233. In controls: 0.299-0.384). However, both ceiling effect and score distribution was best improved with the CHAQ38 and to some extent the CAT2.
Conclusions The overall validity was increased with the CHAQ38, though still not optimally with either of the two scoring models (CAT1/CAT2). This calls for more complex assessment tools in well-functioning JIA-patients in the future.
Disclosure of Interest None Declared
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