Trends in Initiation of Disease‐Modifying Antirheumatic Drugs for Rheumatoid Arthritis Among Commercially Insured Adults in the United States, 2001–2021

ABSTRACT Objective To evaluate patterns in disease‐modifying antirheumatic drugs ( DMARDs ) initiations between 2001 and 2021 among adults with Rheumatoid Arthritis ( RA ) in the United States Methods This retrospective cohort study used a US commercial claims database (2001–2021) to identify patients (≥ 18 years) with RA newly initiating a DMARD . We calculated the annual proportion of initiations for 22 DMARDs , categorized as conventional synthetic ( csDMARDs ), biologic ( bDMARDs ), and targeted synthetic ( tsDMARDs ). Secondary analyses examined trends in first‐line non‐ csDMARD initiation and biosimilar uptake. Results We identified 407,728 DMARD initiation episodes among 229,365 unique patients with RA (median age: 50 years [ IQR ], 44–58 years; 79.4% female). There were shifts in DMARD initiations, with csDMARD initiation declining from 79.9% of initiations in 2001 to 54.7% by 2021 ( p < 0.001 for trend). Meanwhile, bDMARDs and tsDMARDs initiations increased from 20.3% in 2001 to 33.1% in 2021 ( p < 0.001) and from 0.1% in 2012 to 12.2% in 2021 ( p = 0.171), respectively. Methotrexate remained the most initiated DMARD over the 21‐year study period, albeit declining from 28.7% to 15.0% of initiations over the study period ( p < 0.001). Adalimumab was the most frequently initiated bDMARD (13.3% in 2003 and 12.2% in 2021; p = 0.05). Among tsDMARDs , tofacitinib initiation peaked at 8.9% in 2019 and declined to 4.4% in 2021, while upadacitinib initiation increased from 1.2% to 7.6% during the same period ( p < 0.001). For secondary analyses, adalimumab was the predominant first‐line b/ tsDMARD initiated (> 40%). Biosimilar uptake stayed below 1%. Conclusion Expanded DMARD options over the last two decades have led to decreased csDMARD initiations and increased b/ tsDMARD initiations, reflecting patient‐ and system‐level factors.