Background/Purpose: Juvenile idiopathic arthritis (JIA) is the most common pediatric rheumatic disorder. An increasing array of disease-modifying antirheumatic drugs (DMARDs) have become available to treat JIA, but few population-based data exist on their uptake over time. We sought to describe trends over the past two decades in DMARD use for children with JIA in the US.

Methods: We used national US commercial claims data (2000-2022) to perform a serial cross-sectional medication utilization study of children ages 1-18 diagnosed with JIA, excluding children with inflammatory bowel disease, lupus, and other systemic rheumatic diseases. 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 initial b/tsDMARD after csDMARD monotherapy. We also conducted subgroup analyses stratified by presence of uveitis diagnosis, age group (1-11, 12-18 years), and sex (male, female).

Results: We identified 20,282 new DMARD use episodes among 13,719 individuals (median age 14 years, 67.5% female). csDMARDs such as methotrexate, while most commonly used overall, declined from 89.5% of new use episodes to 42.9% (2001-2022, p< 0.001 for trend; Figure 1). In contrast, bDMARD use increased (10.5 to 50.7%, 2001-2022, p< 0.001). For tumor necrosis factor inhibitors (TNFi), etanercept peaked at 28.3% (2006) and declined to 4.4% (2022) (p=0.002) (Figure 2). Adalimumab use doubled (7.0 to 14.0%, 2007-2008) after approval for JIA, increasing further after a less painful formulation release (20.2%, 2022, p< 0.001). However, TNFi use declined with rising use of other b/tsDMARDs, especially ustekinumab, tofacitinib (Figure 2), and secukinumab (not shown), and each spiking in use after respective pediatric regulatory approvals. Adalimumab became the leading b/tsDMARD initiated after csDMARDs when a citrate-free formulation became available in 2018 (Figure 3). In the subgroup of those diagnosed with uveitis, the percentage of methotrexate initiations declined from 54.8% in 2005 to 20.0% in 2006 (p< 0.001) as relative use of bDMARDs in this subpopulation increased. DMARD trends in subgroup analyses stratified by age group and sex were mostly consistent with the main analyses. However, methotrexate use was relatively more common among children under age 12 (mean 39.5%, 2001-2022) than among older children (mean 26.3%, 2001-2022). Use of ustekinumab was higher among older children (≥12 years) and boys, while use of infliximab was higher among younger children (< 12 years) and girls. Hydroxychloroquine was among the top 3-4 DMARDs used in both younger and older children from 2001-2022.

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

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/trends-in-new-use-of-disease-modifying-antirheumatic-drugs-in-juvenile-idiopathic-arthritis-among-commercially-insured-children-in-the-united-states-from-2001-2022/