To study self-reported pain early in the disease course of juvenile idiopathic arthritis (JIA) as a predictor of long-term disease outcomes.
Consecutive cases of JIA with disease onset from 1997 to 2000 from defined geographical areas of Norway, Sweden, Finland, and Denmark were prospectively enrolled in this population-based cohort study. Self-reported, disease-related pain was measured on a 10-cm visual analog scale (VAS pain). Inclusion criteria were a baseline visit with a pain score 6 months after disease onset, followed by an 8-year study visit. Remission was defined according to Wallace et al (2004) preliminary criteria. Functional disability was measured by the Childhood Health Assessment Questionnaire and the Child Health Questionnaire Parent Form if the child was age <18 years and by the Health Assessment Questionnaire if age ≥18 years. Damage was scored using the Juvenile Arthritis Damage Index.
The final study cohort consisted of 243 participants, and 120 participants (49%) had oligoarticular onset. At baseline, 76% reported a VAS pain score >0 compared to 57% reporting at 8 years. Half of those who reported baseline pain also reported pain at 8 years but at a lower intensity. Compared to no pain, higher pain intensity at baseline predicted more pain at 8 years, more functional disability, more damage, and less remission without medication. Baseline pain predicted more use of disease-modifying antirheumatic drugs/biologics during the disease course. Participants with oligoarticular JIA reporting pain at baseline were more likely to develop extended oligoarticular JIA or other JIA categories with an unfavorable prognosis.
Early self-reported, disease-related pain among children and adolescents with JIA is common and seems to predict persistent pain and unfavorable long-term disease outcomes.