Long-term anti-TNF therapy and the risk of serious infections in a cohort of patients with rheumatoid arthritis: Comparison of adalimumab, etanercept and infliximab in the GISEA registry

Objective: To evaluate the risk of serious infections (SIs) in RA patients receiving anti-TNF therapy on the basis of the data included in the GISEA register. Methods: The study involved 2769 adult patients with long-standing RA (mean age 53.2 +/- 13.4 years; mean disease duration 9.0 +/- 8.3 years) enrolled in the GISEA register, who had been treated for at least 6 months with TNF inhibitors or had discontinued therapy due to SI: 837 (30%) treated with infliximab (IFN), 802 (29%) with adalimumab (ADA), and 1130 (41%) with etanercept (ETN). Results: 176 patients had experienced at least one of the 226 Sis during the 9 years of treatment with an anti-TNF agent, an overall incidence of 31.8/1000 patient-years (95% CI 25.2-38.3): 23.7/1000 patient-years (95% CI 13.1-34.2) on ADA; 12.8/1000 patient-years (95% CI 6.3-19.4) on ETN and 65.1/1000 patient-years (95% CI 48.4-81.8) on IFN. The risk was higher in the first than in the second year of treatment, but this difference was not statistically significant (p = 0.08) (38.9% of the SIs were recorded in the first 12 months of treatment). The risk of SI was significantly different among the three treatment groups (p<0.0001). Multivariate models confirmed that the use of steroids (p<0.046), concomitant DMARD treatment during anti-TNF therapy (p=0.004), advanced age at the start of anti-TNF treatment (p<0.0001), and the use of IFN or ADA rather than ETN (respectively p<0.0001 and p = 0.023) were strong and statistically significant predictors of infection. Conclusions: Anti-TNF therapy is associated with a small but significant risk of SI that is associated with the concomitant use of steroids, advanced age at the start of anti-TNF treatment, and the type of anti-TNF agent.