OBJECTIVES: Disease-modifying anti-rheumatic drugs (DMARD) are often added to methotrexate (MTX) for managing rheumatoid arthritis (RA). This study examined the factors associated with the first add-on DMARD for RA patients receiving MTX.

METHODS: This retrospective cohort study involved DMARD-naïve patients aged ≥18 with RA initiating MTX (index date) between July 1^st 2012-Dec 30^th 2013, from the MarketScan Claims data. Patients had continuous enrollment for the 6-month pre-index period, and the addition of conventional synthetic (cs) DMARDs, tumor necrosis factor inhibitors (TNFi), biological (b) DMARDs, or non-TNFi bDMARDs was assessed during 1-year post-index period. Combination therapy was defined as having an MTX prescription within the first 30 days after DMARD initiation. A multivariable logistic regression analysis was used to examine the factors associated with the addition of TNFi versus csDMARD. A second multivariable regression evaluated the factors associated with adding any biologics by combining TNFi and non-TNF biologics to bDMARD.

RESULTS: Among 2,665 DMARD-naïve RA patients initiating MTX, majority were added TNFi (550 (58%)), followed by csDMARD (352 (37%)) and non-TNF biologics (40 (4%)). Most of the patients receiving combination therapy were females (79%), from South (46%), and with preferred provider organization (PPO) plan (64.%). Enabling factors of PPO (odds ratio (OR) [95% confidence interval (CI)], 1.40 [1.03-1.89]), need factors of chronic pulmonary disease (1.73[1.02-2.96]), liver disease (4.11 [1.46-11.61]), glucocorticoid injection (1.44 [1.03-2.01]), human leukocyte antigen gene test (1.61 [1.01-2.56]), Elixhauser index (0.93 [0.88-0.98]) and antibodies to mutated citrullinated vimentin test (0.54 [0.30-0.99]) were associated with adding a TNFi. The second model additionally found that enabling factor of metropolitan statistical area (1.49 [1.03-2.16]) was associated with adding any biologics.

CONCLUSIONS: TNFi are often added to MTX regimen for the management of RA. Both enabling and need factors were associated with the addition of TNFi to MTX therapy for managing RA.