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Objective.To estimate the probability of early remission with conventional treatment for each child with juvenile idiopathic arthritis (JIA). Children with a low chance of remission may be candidates for initial treatment with biologics or triple disease-modifying antirheumatic drugs (DMARD).Methods.We used data from 1074 subjects in the Research in Arthritis in Canadian Children emphasizing Outcomes (ReACCh-Out) cohort. The predicted outcome was clinically inactive disease for ≥ 6 months starting within 1 year of JIA diagnosis in patients who did not receive early biologic agents or triple DMARD. Models were developed in 200 random splits of 75% of the cohort and tested on the remaining 25% of subjects, calculating expected and observed frequencies of remission and c-index values.Results.Our best Cox logistic model combining 18 clinical variables a median of 2 days after diagnosis had a c-index of 0.69 (95% CI 0.67–0.71), better than using JIA category alone (0.59, 95% CI 0.56–0.63). Children in the lowest probability decile had a 20% chance of remission and 21% attained remission; children in the highest decile had a 69% chance of remission and 73% attained remission. Compared to 5% of subjects identified by JIA category alone, the model identified 14% of subjects as low chance of remission (probability < 0.25), of whom 77% failed to attain remission.Conclusion.Although the model did not meet our a priori performance threshold (c-index > 0.70), it identified 3 times more subjects with low chance of remission than did JIA category alone, and it may serve as a benchmark for assessing value added by future laboratory/imaging biomarkers.

Objective To describe changes in health-related quality of life (HRQoL) over time in children with juvenile idiopathic arthritis (JIA), relative to other outcomes, and to identify predictors of unfavorable HRQoL trajectories. Methods Children with JIA in the Research in Arthritis in Canadian Children emphasizing Outcomes (ReACCh-Out) cohort were included. The Juvenile Arthritis Quality of Life Questionnaire (JAQQ, a standardized instrument), health-related Quality of My Life (HRQoML, an instrument based on personal valuations), and JIA core variables were completed serially. Analyses included median values, Kaplan-Meier survival curves, and latent trajectory analysis. Results A total of 1,249 patients enrolled at a median of 0.5 months after diagnosis were followed for a median of 34.2 months. The degree of initial HRQoL impairment and probabilities of reaching the best possible HRQoL scores varied across JIA categories (best for oligoarthritis, worst for rheumatoid factor–positive polyarthritis). Median times to attain best possible HRQoL scores (JAQQ 59.3 months, HRQoML 34.5 months), lagged behind those for disease activity, pain, and disability measures. Most patients followed trajectories with minimal or mild impairment; however, 7.6% and 13.8% of patients, respectively, followed JAQQ and HRQoML trajectories with persistent major impairment in HRQoL. JIA category, aboriginal ethnicity, and baseline disease activity measures distinguished between membership in trajectories with major and minimal impairments. Conclusion Improvement in HRQoL is slower than for disease activity, pain, and disability. Improvement of a measure based on respondents’ preferences (HRQoML) is more rapid than that of a standardized measure (JAQQ). Higher disease activity at diagnosis heralds an unfavorable HRQoL trajectory.