The arthritis module has been developed as a supplement to the chronic-generic module with a focus on arthritis–specific physical symptoms and limitations. It comprises two main scales, Impact and Understanding. As in the chronic-generic measure, the scale scores have been transformed to a range of 0 to 100, higher values indicating better arthritis-specific HRQOL. The Impact scale is related to physical symptoms and disease-specific impacts on activities of daily living, well-being and social relations. For clinical interpretation, the impact scale may also be divided into two sub-domains, Pain (3 items, α = .79) and Limitations (6 items, α = .82). The Pain subscale refers to general adaptation to pain and pain-related impact on activities, the Limitation subscale addresses other arthritis-related functional and social limitations due to joint problems and exhaustion. Children with more active or severe arthritis are expected to report lower HRQOL in this domain. The Impact scale is also supposed to be sensitive to treatment changes or improvement of the condition. The Understanding scale has been developed to address feelings of social exclusion and lack of empathy by peers and teachers. This arthritis-specific burden is related to the invisibility of the condition and the fluctuation of symptoms and is assumed to have a greater impact on HRQOL in children with a moderate disease severity. Low HRQOL of the patient in this domain may indicate an unmet need for comprehensive care like health education or cooperation with school based services or other health services.