Infections in patients with rheumatoid arthritis treated with biologic agents

To estimate the incidence rates of serious and nonserious infections in patients with rheumatoid arthritis (RA) who start treatment with a biologic agent, and to compare these rates with those in patients with RA who receive conventional treatment.

Patients enrolled in the German biologics register between May 2001 and September 2003 were included. Treating rheumatologists assessed adverse events and serious adverse events. All adverse events and serious adverse events experienced within 12 months after study entry were analyzed. Propensity score methods were applied to estimate which part of a rate increase was likely to be attributable to differences in patient characteristics.