OBJECTIVES: Evaluate 12 month switch patterns among patients taking anti-TNFs for rheumatoid arthritis (RA) in the context of validating a Rheumatoid Arthritis Outcomes Analyzer (RAOA); a data analysis tool incorporating pharmacy, medical claims, and member eligibility information. METHODS: The study was conducted utilizing claims data from a two large commercial datasets: Cohorts #1 and #2.  Facilitated by the RAOA, medical and pharmacy claims were entered into two distinct datasets for inclusion in the analysis.  Patients were ≥ 18 years of age, received ≥ one traditional (non-biologic) or biologic DMARD between January 2005 and December 2007, and had ≥ two RA diagnoses (ICD-9 CM 714.0X) ≥ two months apart.  For the switch analysis, patients had at least 18 months continuous eligibility; 6 months prior to index date (initial anti-TNF) and treatment naïve, and 12 months post. RESULTS: A total of 2177 (Cohort #1) vs. 1113 (Cohort #2) patients entered the analysis.  In Cohort #1, 426 (19.6%) received adalimumab, 1123 (51.6%) received etanercept and 628 (28.8%) received infliximab as initial treatment.  In Cohort #2, 355 (31.9%) received adalimumab, 509 (45.7%) received etanercept and 249 (22.4%) received infliximab. In both Cohorts, 75% were female.   During the twelve months following the index date, 161 (7.4%) vs. 91 (8.2%) switched to another biologic DMARD; 133 (6.1%) vs. 87 (7.8%) switched to another anti-TNF biologic and 28 (1.3%) vs. 4 (0.4%) to a non anti-TNF biologic DMARD.  Twenty-seven (6.3%) vs. 44 (12.4%) of patients in the adalimumab sub-group switched to an anti-TNF biologic compared to 99 (8.8%) vs. 37 (7.3%) for etenercept and 7 (1.1%) vs. 6 (2.4%) for infliximab. CONCLUSIONS: Analytic tools such as the RAOA will allow payers and policy makers to better understand utilization and treatment patterns easily and quickly.  Replication and validation of outputs from these tools are important to establish the precision of results.