- OBJECTIVE: The systemic onset form of juvenile idiopathic arthritis (SO-JIA) is a very serious chronic illness of childhood. At present, there is no specific tool to measure disease activity for SO-JIA. Our long-term goal is to develop a disease activity measure for SO-JIA using a consensus (Delphi) approach. In preparation for the development of this measure, we interviewed both patients and their parents. We sought to elicit specific items reflecting their perceptions of active disease that may be considered for inclusion in a disease activity measure for SO-JIA. METHODS: SO-JIA patients followed at The Hospital for Sick Children and their parents were chosen by purposive sampling. A trained research coordinator interviewed all participants using open-ended questions to elicit aspects of disease activity (defined as reversible manifestations of disease) of relevance to families. A list of these aspects was then generated and organized by categories to allow item reduction. RESULTS: Fourteen patients (eight females) with a mean age of 11.8 yr (mean disease duration 5.2 yr) and their parents were interviewed. A total of 292 items were generated, with an average of 11 items generated per interview. Arthralgia, ambulation difficulties, rash, decreased energy level and fever were the most common items mentioned by patients and their parents. Mood disturbances, decreased activity levels, arthritis severity and decreased school attendance were also common items identified as relevant aspects of disease activity. CONCLUSION: This study has allowed us to include patient and parent perspectives in preparation for developing a disease activity measure for SO-JIA. The resulting items will be added to future physician surveys in the further development and validation of a disease activity measure for SO-JIA.