Background
The comparative risk of infection associated with non anti-TNF biologics are not well established. Our objective was to compare risk for hospitalized infections between anti-TNF and non-anti-TNF biologics in U.S. veterans with rheumatoid arthritis (RA).
Methods
Using 1998–2011 data from the U.S. Veteran’s Health Administration, we studied RA patients initiating rituximab, abatacept or anti-TNF therapy.. Exposure was based upon days supplied (injections) or usual dosing intervals (infusions). Treatment episodes were defined as new biologic use. Hazard ratios (HR, 95% CI) for hospitalization for a bacterial infection were estimated from Cox proportional hazards models, adjusting for potential confounders.
Results
Among 3152 unique RA patients contributing 4158 biologic treatment episodes to rituximab (n=596), abatacept (n=451), and anti-TNF (n−3111); patient mean age was 60 years, 87% were male. The most common infections were pneumonia(37%), skin/soft tissue(22%), urinary tract(9%), and bacteremia/sepsis(7%). Hospitalized infection rates/100 person-years (95% CI) were 4.4 (3.1, 6.4) for rituximab, 2.8 (1.7, 4.7) for abatacept and 3.0 (2.5, 3.5) for anti-TNF. Compared to etanercept, the adjusted rate of hospitalized infection was not different for adalimumab (HR 1.4, 0.9–2.2), abatacept (HR 1.1, 0.6–2.1), or rituximab (HR 1.4, 0.8–2.6) although was increased for infliximab (HR 2.3, 1.3–4.0). Infection risk was greater for those taking prednisone >7.5mg/day (HR=1.8, 1.3–2.7) and in the highest quartile of C-reactive protein (HR=2.3, 1.4–3.8) and ESR rate (HR= 4., 2.3–7.2)) compared to the lowest quartile.
Conclusions
In older, predominantly male US veterans with RA, the risk of hospitalized bacterial infections associated with rituximab or abatacept was similar to etanercept.