Predictors of early inactive disease in a juvenile idiopathic arthritis cohort: results of a Canadian multicenter, prospective inception cohort study.

OBJECTIVE: To determine early predictors of 6-month outcomes in a prospective cohort of patients with juvenile idiopathic arthritis (JIA).
METHODS: Patients selected were those enrolled in an inception cohort study of JIA, the Research in Arthritis in Canadian Children Emphasizing Outcomes Study, within 6 months after diagnosis. The juvenile rheumatoid arthritis core criteria set and quality of life measures were collected at enrollment and 6 months later. Outcomes evaluated included inactive disease, Juvenile Arthritis Quality of Life Questionnaire (JAQQ) scores, and Childhood Health Assessment Questionnaire (C-HAQ) scores at 6 months.
RESULTS: Thirty-three percent of patients had inactive disease at 6 months. Onset subtype and most baseline core criteria set measures correlated with all 3 outcomes. Relative to oligoarticular JIA, the risks of inactive disease were lower for enthesitis-related arthritis, polyarthritis rheumatoid factor (RF)-negative JIA, and polyarthritis RF-positive JIA, and were similar for psoriatic arthritis. In multiple regression analyses, the baseline JAQQ score was an independent predictor of all 3 outcomes. Other independent baseline predictors included polyarthritis RF-negative and systemic JIA for inactive disease; C-HAQ score and polyarthritis RF-positive JIA for the 6-month C-HAQ score; and active joint count, pain, and time to diagnosis for the 6-month JAQQ score.
CONCLUSION: Clinical measures soon after diagnosis predict short-term outcomes for patients with JIA. The JAQQ is a predictor of multiple outcomes. Time to diagnosis affects quality of life in the short term.