OBJECTIVES: The aim was to estimate the prevalence of rheumatoid arthritis (RA) between 2003 and 2007, examine the real-life treatment patterns, and estimate the cost of managing RA in Taiwan. .METHODS: A retrospective analysis of the medical claims data from the National Health Insurance Research Database (NHIRD) from years 2003-2007 was conducted. Eligible patients were defined as having 1) an outpatient visit with ICD9 code=714.0; 2) an inpatient admission with the ICD9 code=714.0; or 3) a catastrophic card for RA. Medication records were extracted. Information on treatment with NSAIDs, DMARDs, and bio-DMARDs was extracted from the recorded diagnosis. RESULTS: The prevalence rate of RA in Taiwan was found to be around 0.4%. Majority of the patients identified were on NSAIDs (~81%), while the proportion of patients treated with DMARDs increased from 26% to > 35% during the study period. In the first year from initial diagnosis, 13% to 17% patients were treated with DMARDs and 75% with NSAIDs. Etanercept was the first bio-DMARD approved for use in RA in Taiwan in 2003; since its introduction, both the number and proportion of RA patients treated with etanercept increased sharply to 2284 by the end of 2007. Out of 2284, TB was reported in 55 patients, 45 of which were new cases. The average duration from starting etanercept to the date of a TB diagnosis was 461 days. The mean cost per person increased from 379 in 2003 to US$703 in 2007, i.e. nearly doubled. CONCLUSIONS: The findings provide an estimate of RA prevalence and show the significant medical cost of managing RA to the national health care system in Taiwan. A key limitation of the study is that the claims data do not have biological information on disease status and the medical reasons for treatment failure or discontinuation.