Real-world Comparative Effectiveness of Methotrexate-based Combinations for Rheumatoid Arthritis: A Retrospective Cohort Study

Purpose: Guidelines recommend using disease-modifying antirheumatic drugs (DMARDs) in combination with methotrexate (MTX) for patients with rheumatoid arthritis (RA) after monotherapy. Little is known about the real-world comparative effectiveness of these MTX-DMARD combinations. This study compared the effectiveness of various MTX-based DMARD combinations for patients with RA initiating MTX-DMARD combination therapy using administrative claims database.Methods: This retrospective cohort study included adults (aged >= 18 years) with RA who initiated MTX combina-tion treatment with conventional synthetic DMARDs (csDMARDs), tumor necrosis factor inhibitor (TNFi) biologic DMARDs (bDMARDs), non-TNFi bDMARDs, or targeted synthetic DMARDs (tsDMARDs) between July 1, 2012, and December 31, 2013 (index date), from the MarketScan Commercial Claims Data. Patients had continuous en-rollment from the 6 months of preindex period until the 12 months of postindex period. The MTX-based DMARD combination therapy cohort was defined as >= 1 MTX prescription in the first 30 days from the index date and >= 14 days overlapping use of the prescription fills of the MTX and the index DMARD. Effectiveness was measured by using the claims algorithm (dosing, switching, addition, oral glucocorticoid use, or multiple glucocorticoid injection). Propensity score analysis with the inverse probability of treatment weighting (PS-IPTW), estimated by using the generalized boosted machine learning method, was used to balance the distribution of baseline variables between the combination groups. Multivariable logistic regression using PS-IPTW was conducted to compare the effectiveness of the combination groups. Sensitivity analysis evaluated the modified effectiveness algorithms or the time to the first treatment failure.Findings: A total of 3174 adult patients with RA starting an MTX-DMARD combination therapy were identi-fied (mean [SD] age, 50 [9] years), including 1568 (49%) initiating a csDMARD + MTX, 1343 (42%) initiating TNFi + MTX, and 240 (8%) initiating non-TNFi bDMARD + MTX, and 23 (1%) initiating tsDMARD + MTX. Owing to the small sample, the tsDMARD combination group was not included in the comparative analysis. Algorithm -based therapy effectiveness was found in 9.95% of the csDMARD + MTX, 20.48% of the TNFi + MTX, and 20.83% of the non-TNFi + MTX groups. PS-IPTW showed that the csDMARD combination is less effective (adjusted odds ratio, 0.422; 95% CI, 0.341-0.524) than the TNFi combination; however, the non-TNFi biologic combination had similar effectiveness (aOR, 1.063; 95% CI, 0.680-1.662) compared to the TNFi combination. Sensitivity analyses confirmed the main results.Implications: Among RA patients initiating MTX-DMARD combinations, both non-TNFi biologics and TNFi-based combinations with MTX were equally effective, but csDMARD + MTX was less effective than the TNFi plus MTX.