Long-term outcomes in juvenile idiopathic arthritis: 18 years of follow-up in the population-based Nordic Juvenile Idiopathic Arthritis (JIA) cohort.

Objectives - This study assessed the long‐term course, remission rate and disease burden in juvenile idiopathic arthritis (JIA) 18 years after disease onset in a population‐based setting from the early biologic era. Methods - A total of 510 consecutive cases of JIA with disease onset between 1997 and 2000 from defined geographic regions in Denmark, Norway, Sweden and Finland were prospectively included in this 18‐year cohort study. At the follow‐up visit, patient‐reported, demographic and clinical data were collected. Results - The study included 434 (85%) of the 510 eligible JIA participants. The mean age ± SD was 24.0 ± 4.4 years. The median juvenile arthritis disease activity (JADAS71) score was 1.5 (IQR 0‐5), with the ERA category of JIA having the highest median score, 4.5 (IQR 1.5–8.5) (P=0.003). In this cohort, 46% still had active disease, and 66 (15%) were treated with synthetic disease‐modifying anti‐rheumatic drugs and 84 (19%) with biologics. Inactive disease indicated by JADAS71 Conclusions - A high prevalence of the JIA cohort did not achieve CR despite new treatment options during the study period. The ERA category showed the worst outcomes and, in general, there is still a high burden of disease in adulthood for JIA