We aimed to evaluate the comparative risk of hospitalized infection among patients with rheumatoid arthritis (RA) who initiated abatacept versus a tumor necrosis factor inhibitor (TNFi).

Using claims data from Truven MarketScan database (2006-2015), we identified patients with RA ages ≥18 years with ≥2 RA diagnoses who initiated treatment with abatacept or a TNFi. The primary outcome was a composite end point of any hospitalized infection. Secondary outcomes included bacterial infection, herpes zoster, and infections affecting different organ systems. We performed 1:1 propensity score (PS) matching between the groups in order to control for baseline confounders. We estimated incidence rates (IRs) and hazard ratios (HRs) with 95% confidence intervals (95% CIs) for hospitalized infection.

We identified 11,248 PS-matched pairs of patients who initiated treatment with abatacept and TNFi with a median age of 56 years (83% were women). The IR per 1,000 person-years for any hospitalized infection was 37 among patients who initiated treatment with abatacept and 47 in those who initiated treatment with TNFi. The HR for the risk of any hospitalized infection associated with abatacept versus TNFi was 0.78 (95% CI 0.64-0.95) and remained lower when compared to infliximab (HR 0.63 [95% CI 0.47-0.85]), while no significant difference was seen when compared to adalimumab and etanercept. The risk of secondary outcomes was lower for abatacept for pulmonary infections, and similar to TNFi for the remaining outcomes.

In this large cohort of patients with RA who initiated treatment with abatacept or TNFi as a first- or second-line biologic agent, we found a lower risk of hospitalized infection after initiating abatacept versus TNFi, which was driven mostly by infliximab.