Rheumatoid arthritis disease-modifying antirheumatic drug intervention and utilization study: safety and etanercept utilization analyses from the RADIUS 1 and RADIUS 2 registries.

Objective: to report the rates of serious adverse events (SAE), serious infectious events (SIE), and events of medical interest (EMI) in patients receiving etanercept; to identify the risk factors for SAE, SIE, and EMI; and to report time to switching from etanercept therapy, reasons for switching, and time to restarting treatment with etanercept in patients with rheumatoid arthritis (RA) in US clinical practice.

Methods: adults ≥ 18 years of age who fulfilled the 1987 American Rheumatism Association criteria for RA were eligible for enrollment in 2 prospective, 5-year, multicenter, observational registries. RADIUS 1 (Rheumatoid Arthritis DMARD Intervention and Utilization Study) enrolled patients with RA who required a change in treatment [either an addition or a switch of a biologic or nonbiologic disease-modifying antirheumatic drug (DMARD)]. In RADIUS 2, patients with RA were required to start etanercept therapy at entry. Patients were seen at a frequency determined by their rheumatologist. RADIUS 1 and RADIUS 2 were registered under the US National Institutes of Health ClinicalTrials.gov identifiers NCT00116714 and NCT00116727, respectively.

Results: in these patients, SAE, SIE, and EMI occurred at rates comparable to those seen in clinical trials. No unexpected safety signals were observed. Rates for SAE, SIE, and EMI in etanercept-treated patients were comparable to rates observed in patients receiving methotrexate monotherapy and did not increase with greater exposure to etanercept therapy.

Conclusion: the RADIUS registries provide a better understanding of the safety of etanercept in patients with RA in the US practice setting.