Background Information regarding longer-term outcomes in JIA largely pre-date the introduction of biologic therapies and have been cross-sectional.
Objectives The aim of this study was to assess outcomes over the first 5 years of disease in children diagnosed with oligoarticular and polyarticular JIA since 2001.
Methods Children with oligoarthritis, rheumatoid-factor (RF) negative or positive polyarthritis were selected if recruited to the Childhood Arthritis Prospective Study (CAPS), a UK multicentre inception cohort, between October 2001 and January 2011. The following outcomes were assessed annually to five years and included in this analysis: functional ability (Childhood Health Assessment Questionnaire (CHAQ)), the absence of limited joints, overall psychosocial health (psychosocial scale on the Child Health Questionnaire (CHQ)) and the proportion of children with CHQ psychosocial scores two standard deviations below the population mean (CHQ psychosocial<30).
Outcomes were assessed descriptively over time and differences between subtypes were assessed by applying multilevel (patient-level) zero-inflated negative binomial (CHAQ), logistic (absence of limited joints, percent CHQ psychosocial<30) and linear (CHQ psychosocial) regression analyses, adjusting for gender, age at presentation and hospital.
Results Of 832 children, 70% were female, 68% had oligoarticular, 28% RF-negative and 5% RF-positive polyarticular JIA. Eighty four percent had ever been treated with NSAIDs, 74% corticosteroids, 55% with DMARDs and 21% with biologics within follow-up.
Baseline CHAQ was good to moderate (median 0.8, IQR 0.1 to 1.4) and only 21% of children had no limited joints reported at this time. CHQ psychosocial scores (median 50, IQR 39 to 55) were moderate, with 11% children scoring at least two standard deviations under the population mean. Overall improvements were evident in all outcomes over the first year then remained stable with no further improvements at the cohort level evident to five years.
Patients with RF-negative polyarthritis experienced significantly poorer outcomes across all variables than those with oligoarthritis. Those with RF-positive polyarthritis recorded similar CHAQ scores to patients with RF-negative polyarthritis but had the lowest odds of no limited joints (OR: 0.4, 95% CI 0.3 to 0.7) and the poorest CHQ psychosocial scores (4.8 points worse and 4.7 times the odds of scores <2 standard deviations of population mean), compared with those with oligoarthritis.
Conclusions On average, the largest improvement in functional ability, limited joints and psychosocial health occur in the first year following diagnosis, perhaps confirming the importance of early treat-to-target strategies. Patients with polyarticular JIA subtype have poorer parent and physician-reported outcomes than those with oligoarthritis.
Disclosure of Interest None declared