Juvenile Idiopathic Arthritis, Earnings and Work Loss: A Nationwide Matched Cohort Study.

Objective: This study compares trajectories of earnings and work loss in individuals with juvenile idiopathic arthritis (JIA) versus matched comparators from the general population.

Methods: Patients with JIA (n=4737) were identified in the Swedish National Patient Register (2001-2017) and individually matched to up to 5 general population comparators on birth year, sex, and residence county (n=23,645). Earnings and work loss data were retrieved from nationwide registers from age 18y. Differences between patients with JIA and general population comparators were estimated using linear regression, adjusted for sex, age, age at identification, calendar year, as well as parental education, work loss and earnings.

Results: During a median of 11 years follow-up, patients with JIA had 5.5% lower earnings than matched comparators (mean annual difference -€736 [95%CI -1026, -445]. The difference in earnings was larger before than after age 26y. Beyond age 26y, the difference in earnings was less than 4%. Patients with JIA had more work loss than matched comparators throughout follow-up (mean difference 11 days/year [95%CI 8-13]). This difference was consistent throughout follow-up, but significant effect modification with calendar period of entry (<2005 vs ≥2005) was found, with later entry associated with lower work loss.

Conclusion: Patients with JIA had lower mean annual earnings and higher work loss than matched general population comparators, but earnings differences diminished in magnitude with age and work loss diminished with calendar period of identification. In JIA, a minority of patients accounts for the majority of the negative impact on economic outcomes, which persists into adulthood.