Trends in New Use of Disease-Modifying Antirheumatic Drugs in Juvenile Idiopathic Arthritis Among Commercially Insured Children in the United States from 2001-2022.

Objective: To describe recent trends in DMARD use for children with juvenile idiopathic arthritis (JIA) in the US.

Methods: We used commercial claims data (2000-2022) to perform a serial cross-sectional utilization study of children ages 1-18 diagnosed with JIA. Initiations of conventional synthetic (cs), biologic (b), or targeted synthetic (ts) DMARDs were identified after a ≥12-month baseline and expressed as percentage of all new DMARD initiations per year, by category, class, and individual agent. Trends were evaluated using linear regression. Secondarily, we examined first b/tsDMARDs initiated after csDMARD monotherapy.

Results: We identified 20,258 new DMARD use episodes among 13,696 individuals (median age 14 years, 67.5% female). csDMARDs, while most commonly used overall, declined from 89.5% of new use episodes to 43.2% (2001-2022, p<0.001 for trend). In contrast, bDMARD use increased (10.5-50.0%, p<0.001). For tumor necrosis factor inhibitors (TNFi), etanercept peaked at 28.3% (2006) and declined to 4.2% (2022) (p=0.002). Meanwhile, adalimumab use doubled (7.0-14.0%, 2007-2008) after JIA approval, increasing further following a less painful formulation release (20.5%, 2022, p<0.001). However, overall TNFi use has declined with increasing use of other b/tsDMARDs, particularly ustekinumab, secukinumab, and tofacitinib. By 2022, adalimumab was the most common b/tsDMARD initiated first after csDMARDs (77.8%).

Conclusion: Among commercially insured children with JIA in the US, new b/tsDMARD use is rising while new csDMARD use declines. For b/tsDMARDs, adalimumab is most used and the predominant b/tsDMARD initiated first after csDMARDs. Patterns in DMARD use for JIA have evolved relative to multiple factors, including regulatory approvals and tolerability.