Adults With JIA Show Higher Comorbidity Burden and Mortality

A nationwide Norwegian register-based matched cohort study was reported in Rheumatology. It found higher 5-year prevalences of several comorbidities and autoimmune conditions in adults with juvenile idiopathic arthritis (JIA) than matched population comparators. Prospective all-cause mortality was also higher.

Using Norwegian Patient Registry data, investigators identified adults with at least two JIA-specific ICD-10 diagnoses after age 18. Cases were identified from 2009 through 2024. Patients were matched 1:10 by age, gender, and centrality index. Mortality analyses included 2,932 adults with JIA and 29,097 comparators. Five-year comorbidity analyses included 2,896 and 28,966, respectively.

Five-year hypertension prevalence was 3.6% in adults with JIA and 1.4% in comparators. Chronic kidney disease prevalence was 0.5% and 0.2%, respectively. Other ischemic heart disease was recorded in 1.0% and 0.6%, respectively. That comparison was not significant after Bonferroni correction. Higher prevalences were also reported for type 1 diabetes (1.7% vs 0.7%) and celiac disease (1.4% vs 0.7%). Autoimmune thyroiditis (0.3% vs 0.1%) and autoimmune alopecia (0.4% vs 0.1%) were also more prevalent in the JIA group.

Mortality follow-up lasted approximately 15 years. Rates were 2.39 vs 1.80 per 1,000 person-years, with a hazard ratio of 1.33 (95% CI, 1.03-1.72). Among adults with JIA, recent or current disease-modifying antirheumatic drug (DMARD) exposure was not associated with a significant difference in age- and gender-adjusted mortality. The hazard ratio was 0.77 (95% CI, 0.43-1.36).

The authors cautioned that the case definition excluded adults diagnosed in childhood who received no specialist care during the study, including those in persistent drug-free remission. They said this created selection bias toward active disease requiring follow-up. They also cited possible cardiovascular detection bias, absent disease-activity data and reasons for DMARD nonuse, and physician-dependent coding. The authors concluded that comorbidity prevalence and mortality were similar between those with and without recent or current DMARD exposure.

Source: Bardan I, Sundbakk LM, Sexton J, et al. Comorbidity and mortality in adults with juvenile idiopathic arthritis: a nationwide Norwegian register-based matched cohort study. Rheumatology. 2026. doi:10.1093/rheumatology/keag507