Background Rheumatoid arthritis (RA) is a chronic, inflammatory disease with joint destruction and permanent disability. Biologic agents offer a better outcome when disease is not adequately controlled by DMARDs. Nevertheless, many concerns still exist about the safety of biologics compared to classical DMARDs treatment.
Objectives The purpose of the study was to test the hypothesis that adverse events (AEs), including severe infections and malignancies, are more common in patients receiving biologics than in those treated with DMARDs.
Methods This study included data from 1143 patients followed in our outpatient academic clinic for whom each severe infection and malignancy was identified. Relative risks were then calculated by comparing the rates of these events. Sub-categories of adverse events were created to clarify what type of infection and/or cancer were observed. Finally, an estimate of survival by Kaplan-Meier method was calculated for these two major adverse events. The experimental group, including patients who were treated with biological agent at any time and the control group, patients who have never taken any biological agent, were compared across these survival curves.
Results We included 1143 patients (74% female, mean age of 51.3 (14.2) years, 75% treated with corticosteroids and 7% with diabetes), 604 (53%) were exposed to biologics and 539 (47%) controls. There were 226 severe infection in the biological group with an IR of 4.89 events/100 patient years (IRR=2.1 95% CI 1.7 to 2.5) as compared with 168 and 2.35 events/100 PY with DMARDs only. In the biological group, increase risk was observed for skin, musculoskeletal, pulmonary, urinary, mycobacterial and herpes zoster infection. The relative risk associated with the use of biological agents in the treatment of rheumatoid arthritis for the development of malignancy was 1.0 (confidence interval 95%: 0.7-1.4) without any significant differences among type of cancer. Survival rates are presented in the figure.
Conclusions This study showed a significant increase in the incidence of severe infections in patients exposed to bioiogical agent. During a mean follow-up of 11 years, no significant risk to develop a cancer was observed. Further longterm observation of severe infection and malignancy in severe RA patients treated with biologics are still needed.
Disclosure of Interest None declared