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

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.