1223 - Drug Survival and Long-Term Dose Comparison of Etanercept and Infliximab in Rheumatoid Arthritis Patients

Monday, November 7, 2011: 9:00 AM-6:00 PM
Hall F2 - Poster Hall (McCormick Place West)
Brian D. Hanna, McMaster University, Ontario, Kitchener, ON and Alpesh Shah, Community Rheumatology Clinic, Etobicoke, ON
Presentation Number: 1223

Background/Purpose: Reports from observational studies show that anti-TNF drug adherence rates in rheumatoid arthritis are higher for etanercept compared with infliximab. Clinical practice shows that not all rheumatoid arthritis patients respond to the 3 mg/kg dose of infliximab, leading some rheumatologists to use higher doses and/or reduce the dosing interval for infliximab. The purposes of this study are: 1) to compare dosing patterns and drug survival rates of etanercept and infliximab, and 2) to compare the initial dose with the optimal, any escalated and the last dose administered for infliximab in rheumatoid arthritis patients in a community based practice.

Method: This study is a retrospective analysis of rheumatoid arthritis patients treated between June 2000 and December 2010 at community rheumatology clinic, starting treatment with either infliximab or etanercept, as a first biologic agent. Information was collected on age, sex, diagnosis, disease duration, previous and ongoing DMARDs, biologic dose, treatment start and termination dates as well as cause of withdrawal. Treatment groups were compared by baseline characteristics, dosing patterns and drug survival. The overall drug survival was compared using survival data with Kaplan-Meier plots. An optimal dose for infliximab was identified as the dose raised in mg/kg or a decrease in dosing interval by six months of treatment to achieve adequate response.   

Result: A total of 116 patients (etanercept: 79 and infliximab : 37) were included in the analysis. All etanercept-treated patients were maintained with 50 mg per week therapy. Mean optimal dose of infliximab was 4.23 ± 1.29 mg/kg and majority of them given at every 8 week interval. Subsequently, 51.4% patients in the infliximab group required dose escalation to 4.51 ± 1.14 mg/kg. Of these, majority (73.8%) patients required infliximab at every 6 week intervals. Median drug survival time for the etanercept group was 58 months, for the infliximab group at optimal doses was 27 months and for the optimal plus escalated doses was 88 months. 

Conclusion: In this study of real-world patients half of the patients in the infliximab group required dose escalation. Drug survival rate was higher with etanercept and the escalated infliximab groups compared with infliximab at initial and optimal doses over ten years of follow-up. 

Keywords: etanercept, infliximab and rheumatoid arthritis (RA)

Disclosure: B. D. Hanna, None; A. Shah, None.