OBJECTIVES: This case study aims to evaluate the long-term utilization and safety of two biological agents- etanercept and adalimumab in treating Taiwanese rheumatoid arthritis (RA) patients.METHODS: This cohort study used a population-based claim-data from the Kaopin Division of Taiwanese National Health Insurance during March 2006 to June 2009. Adult RA outpatients were identified by diagnosis code, and followed from the first prescription date (index date) of biological agents up to two months after discontinuation (prescription stop for more than 30 days) or the end of study. Prescription continuation rate between two drugs was evaluated using Kaplane-Meier survival curves and compared by the log-rank test. The frequencies of infectious events for new users of biological agents were also collected and the odds ratios of infectious events comparing etanercept against adalimumab were evaluated by logistic regression.RESULTS: Of all, 190 new users (mean age 53.43±11.61 years; 83.68% female) were assessed. Most patients (70.53%) were prescribed biological agents in medical centers and 63.16% of them used etanercept. Total cumulative exposure time is 184.32 patient-years (145.86 patient-years in etanercept group, 38.46 patient-years in adalimumab group). Overall continuation rate for biological agents is 78.06% after one year, 55.04% after two year. The median continuation time is 836 days (95%CI 541, 972). Twenty-nine infectious events were detected; the most frequent events are pneumonia (7 events) and tuberculosis (6 events). Patients who treated by etanercept had more infectious events than patients treated with adalimumab (OR: 5.99; 95%CI 1.55, 40.00).CONCLUSIONS: This study demonstrated that only half RA patients sustained their original biological therapy for more than two year. Furthermore, RA patients who treatd with etanercept acquired higher risk of infectious events. However, it is still necessary to further find out reasons for discontinuation and to explore the causality between biological agents and infectious events.