Abstract
BACKGROUND: The risk of subsequent infections in rheumatoid arthritis (RA) patients who receive biologic therapy after a serious infection is unclear. OBJECTIVE: To compare the subsequent risk of hospitalised infections associated with specific biologic agents among RA patients previously hospitalised for infection while receiving anti-tumour necrosis factor (anti-TNF) therapy. METHODS: Using 2006-2010 Medicare data for 100% of beneficiaries with RA enrolled in Medicare, we identified patients hospitalised with an infection while on anti-TNF agents. Follow-up began 61 days after hospital discharge and ended at the earliest of: next infection, loss of Medicare coverage or 18 months after start of follow-up. We calculated the incidence rate of subsequent hospitalised infection for each biologic and used Cox regression to control for potential confounders. RESULTS: 10 794 eligible hospitalised infections among 10183 unique RA patients who contributed at least 1 day of biologic exposure during follow-up. We identified 7807 person-years of exposure to selected biologics--333 abatacept, 133 rituximab and 7341 anti-TNFs (1797 etanercept, 1405 adalimumab, 4139 infliximab)--and 2666 associated infections. Mean age across biologic exposure cohorts was 64-69 years. The crude incidence rate of subsequent hospitalised infection ranged from 27.1 to 34.6 per 100 person-years. After multivariable adjustment, abatacept (HR: 0.80, 95% CI 0.64 to 0.99) and etanercept (HR: 0.83, 95% CI 0.72 to 0.96) users had significantly lower risks of subsequent infection compared to infliximab users. CONCLUSIONS: Among RA patients who experienced a hospitalised infection while on anti-TNF therapy, abatacept and etanercept were associated with the lowest risk of subsequent infection compared to other biologic therapies.