(020) Initiation Trends of Disease-Modifying Antirheumatic Drugs for Rheumatoid Arthritis Among Adults in the United States from 2001 to 2021

Background: While many new disease-modifying antirheumatic drugs (DMARDs) have been approved for rheumatoid arthritis (RA) in the past two decades, there is limited research evaluating how these expanded options have influenced real-world prescribing patterns.

Objectives: To evaluate patterns of DMARD initiations between 2001 and 2021 among commercially insured US adults with RA.

Methods: This serial cross-sectional study used MarketScan data (2001-2021), to identify a cohort of adults (>18 years) with RA newly initiating a DMARD. For each calendar year, we calculated the proportion of initiations for individual DMARDs. Twenty-two DMARDs were examined and grouped into categories of: conventional synthetics (csDMARDs), biologic (bDMARD), and targeted synthetics (tsDMARDs). Secondary analyses included examination of trends in the first-line use of non-csDMARDs, and uptake of biosimilars.

Results: We identified 407,728 DMARD initiation episodes, corresponding to 229,365 unique RA patients (median age, 50 [IQR, 44-58 years]; 79.4% female). Analysis revealed significant shifts in DMARD preferences, with csDMARD use declining from 79.7% 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 2014 to 12.2% in 2021 (p < 0.001), 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 bDMARDs (13.3% in 2003 and 12.2% in 2021; p=0.05). Among tsDMARDs, tofacitinib use peaked in 2019 (8.9%) and declined to 4.4% by 2021, while upadacitinib increased from 1.2% to 7.6% during the same period (p < 0.001). For secondary analyses, adalimumab was the predominant first-line non-cs-DMARD initiated (>40%). Uptake of biosimilars remained very low ( < 1%) throughout the study period.

Conclusions: This study provides insights into the evolving landscape of DMARD treatment for RA in the US. The observed decline in csDMARDs with increasing use of bDMARDs and tsDMARDs suggest changing preferences or accessibility factors. Monitoring real-world utilization patterns remain crucial for refining treatment approaches as new DMARDs emerge. Future research should consider post-2021 trends, the impact of expanding availability of biosimilars in the US, and recent safety communications on Janus kinase (JAK) inhibitors.