OBJECTIVES: To evaluate the relationship between switching patterns among anti-TNFs and healthcare costs in rheumatoid arthritis (RA) patients. METHODS: A retrospective study utilizing the PharMetrics managed-care claims database was conducted. The first anti-TNF encounter among RA patients between January 1, 2001 and January 1, 2004 was identified. Patients were required to have a minimum of 12-months of continuous plan-eligibility prior to and following their index date. RA-related healthcare costs were compared between two mutually exclusive cohorts: patients who switched to another anti-TNFs versus patients who did not switch. Descriptive and Chi-square statistical analyses were conducted to determine if differences existed between the two cohorts. Multivariate analysis was performed to adjust for confounding factors. RESULTS: In total, 2231 patients were analyzed. Over two-thirds of all patients were female; the mean age was 50.2 years. The Charlson Co-morbidity Index (CCI) and disease staging were similar between the two cohorts. During the 12-month follow-up, 207 patients (9.3%) were switched from one anti-TNF to another. The average time before switching was 187 days. Compared with patients who did not switch, patients who switched had higher total health care costs ($19,256 versus $16,753, P=0.005), physician visits ($1350 versus $900, P<0.0001), inpatient hospitalizations ($1213 versus $899, P=0.472), ER visits ($33 versus $30, P=866), pharmacy costs ($15,478 versus $13,445, P=0.001), except outpatient ($402 versus $509, P=0.511) and other costs ($704 versus $919, P=0.598). After adjusting for age, gender, CCI, and pre-index period healthcare costs, patients who switched had significantly higher total and medical costs than patients who did not switch. CONCLUSION: The rate of switching and time before switching are important measures of the effectiveness of RA treatment in real world practice. This study found that switching between anti-TNF therapies is associated with higher healthcare costs.