AB0766 Switching among tumor necrosis factor (tnf)-blockers in us veterans with rheumatoid arthritis (ra)

Background Tumor necrosis factor (TNF)-blockers are effective in treating RA, but the benefit of switching between TNF-blockers is less clear. Objectives To examine switching, costs and factors associated with switching between adalimumab (ADA), etanercept (ETN), and infliximab (INF) in patients (pts) in the Veterans Affairs Rheumatoid Arthritis (VARA) registry following their first VA episode of TNF-blocker use. Methods VARA is a longitudinal, observational, cohort study of US veterans with RA. It links to VA pharmacy and administrative data and documents longitudinal assessments of RA disease activity and outcomes. VARA patients initiating ADA, ETN, or INF from March 2003 to Sept 2010 were identified and followed until Sept 2011. A treatment course was defined as continuous TNF-blocker use without ≥90-day gap. Cost of TNF-blockers with and without drug administration costs was determined for first and second courses. Results Data from 563 RA pts (204 ADA, 290 ETN, 69 INF) initiating therapy were analyzed. During observation (5.2±2.1 years), 47% had a single TNF-blocker course, 25% restarted the same TNF-blocker and 28% switched. Patients with a single course were older than pts with multiple courses. In the 61 pts with pre- and post-treatment DAS28, pts who switched had higher DAS28 on treatment than pts restarting the same TNF-blocker. DAS28 was similar before and after the second TNF-blocker course in both groups. Patients with ≥25% increase in dose or ETN as initial therapy were more likely to switch. In pts who switched, initial annualized costs were numerically higher in the first course and statistically significantly higher during the second course than for pts who restarted their TNF-blocker. Conclusions In VARA, approximately 50% of pts had at least 1 course of TNF-blocker treatment. Patients who switched had higher DAS28 scores during the initial course, a history of dose escalation with the initial agent and higher costs. Due to potential confounding factors inherent in observational studies, more research is needed to understand reasons for switching and the effects of switching TNF-blockers on overall outcomes in RA. Acknowledgements Research funded by VA Research Program and Immunex Corporation, a wholly owned subsidiary of Amgen Inc., and by Wyeth, which was acquired by Pfizer Inc. in October 2009. Disclosure of Interest G. Cannon Grant/research support from: Amgen, S. DuVall Grant/research support from: Amgen, Anolinx LLC, Genentech, F. H