Changing patterns in treatment, remission status and categories in a long-term Nordic cohort study of juvenile idiopathic arthritis

Arthritis Care Res (Hoboken). 2022 Jan 10. doi: 10.1002/acr.24857. Online ahead of print.

Abstract

Objective: To explore sustainability of achieved remission off medication and defined ILAR categories in juvenile idiopathic arthritis (JIA). To describe the trajectory of disease course over time by comparing treatment, disease activity and ILAR categories from baseline, 8 and 18 years of disease.

Methods: Included were 373 of the 510 initially recruited consecutive cases of JIA from the prospective longitudinal, population-based Nordic JIA cohort with disease onset during 1997-2000 from Denmark, Norway, Sweden, and Finland in an 18-year follow-up study. Clinical data was collected consecutively at baseline, 8 and 18 years of disease, and evaluated regarding treatment, disease activity and ILAR category.

Results: Significantly more patients (70%) were off medication after 18 years of follow-up compared to after 8 years (59.7%); nevertheless, the number of patients in remission had not increased (52% versus 51%). Twelve percent of patients changed ILAR category between 8 and 18 years after disease onset. Almost half of the changes were due to updated information about heredity in a first degree relative. In the same period, the psoriatic group increased significantly in number (p<0.001) contrasting the oligoarticular category, which decreased (p=0.02). The undifferentiated group increased 24% from 8 to 18 years, however, this was not significant (p=0.06).

Conclusion: In this Nordic JIA cohort study the remission rate did not increase even though significantly more patients were off medication at the 18-year follow-up compared to 8 years after disease onset. The distribution of patients in the ILAR categories continued to change significantly throughout the 18-year study period.