To assess the reliability, validity, and sensitivity to change of the Norwegian version of the childhood Health Assessment Questionnaire (CHAQ) and to examine the relationship between disability, disease severity, and psychosocial factors in patients with early juvenile rheumatoid arthritis (JRA).
Physical functioning was assessed by the CHAQ in 109 patients (median age 6.6 years, range 1.0-16.6) with JRA and a median of 4 months' (range 2-23) disease duration. Eighty-three patients were reassessed after a median of 6 months (range 3-21). Psychosocial functioning was assessed by the Child Behavior Checklist (n=39).
The internal consistency of the CHAQ was good (Cronbach's alpha=0.83). The test-retest and parent-patient correlations were high [intraclass correlation coefficients 0.85 (n=18) and 0.75 (n=20), respectively, p < 0.001]. The CHAQ correlated moderately with number of tender, swollen and mobility restricted joints, morning stiffness, C-reactive protein, pain, and patients' and physicians' global assessments [correlation coefficients (r) ranging from 0.55 to 0.30, p < 0.01], but weakly with erythrocyte sedimentation rate (r=0.17, NS). The CHAQ also correlated with low levels of social competence (r=-0.49, p < 0.05) and high levels of internalizing behavior problems in the patients (r=0.43, p < 0.01) and low education levels of the mothers (r=-0.31, p < 0.01). Pain (beta 0.45, p < 0.001), number of swollen joints (beta 0.31, p < 0.001), and internalizing behavior problems (beta 0.45, p < 0.01) were predictors of disability. The median CHAQ changed from 0.25 to 0.00 (p < 0.05) in the 41 patients who improved, from 0.31 to 0.85 (p < 0.05) in the 18 patients whose condition was worse, and from 0.50 to 0.59 (NS) in the 24 patients whose condition was unchanged after 6 months. The effect size of the change was small (0.28) in those who improved and moderate (0.54) in those who became worse.
The Norwegian version of the CHAQ is a reliable and valid instrument for measuring disability in children with early JRA. Pain, joint inflammation, and psychosocial factors are the most important correlates of disability and the CHAQ is sensitive to clinical change.