To study the impact of chronic arthritis on health related quality of life by means of two self-reported tools: the parents' version of the Childhood Health Assessment Questionnaire (CHAQ) and the Childhood Health Questionnaire PF50\'ae (CHQ).\par
Both tools were filled in after proper instructions by 36 parents, during 1-2 clinic visits. The Disability Index (CHAQ) and the Physical and Psychosocial scores (CHQ) were compared to the core set of outcome measures, namely 1) physician's global assessment, 2) parents' global assessment, both scored by 10 cm visual analogue scale, 3) number of joints with active arthritis, 4) number of joints with limited range of motion, 5) erythrocyte sedimentation rate.\par
There was significant difference for all measures of disease activity, being higher in the polyarticular as compared to oligoarticular except for erythrocyte sedimentation rate, parents' global assessment, and psychosocial score. This leads to different parents' perceptions of disease activity and outcome. The responsiveness of the outcome measures during two follow-up visits of patients receiving active treatment indicated better responsiveness of physicians' global assessment among the subjective measures, and intermediate responsiveness of the self-reported measures in comparison to the number of active and limited joints, and erythrocyte sedimentation rate. \par
The responsiveness of two health related quality of life tools indicates their relative sensitivity for assessing clinical improvement during active treatment in Juvenile Idiopathic Arthritis patients.\par