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

Objective: The objective of this study is to describe recent trends in disease-modifying antirheumatic drug (DMARD) use for children with juvenile idiopathic arthritis (JIA) in the United States.

Methods: We used commercial claims data (2000-2022) to perform a serial cross-sectional utilization study of children aged 1 to 18 that were diagnosed with JIA. Initiations of conventional synthetic DMARDs (csDMARDs), biologic DMARDs (bDMARDs), or targeted synthetic DMARDs (tsDMARDs) were identified after a ≥12-month baseline and expressed as a percentage of all new DMARD initiations per year, by category, class, and individual agent. Trends were evaluated using linear regression. We also examined the first bDMARDs and 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, although most 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% in 2006 and declined to 4.2% in 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% in 2022, P < 0.001). However, overall TNFi use has declined with increasing use of other bDMARDs and 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 United States, new b/tsDMARD use is rising and new csDMARD use is declining. For b/tsDMARDs, adalimumab is most used and is 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.