Background TNF-α inhibitors etanercept, infliximab and adalimumab have been used for more than 10 years to treat moderate to severe rheumatoid arthritis (RA). Different studies reported different drug survival rate for these drugs. Clinical practice also shows that not all RA patients respond to the 3 mg per kg dose of infliximab, leading some rheumatologists to use higher doses and/or reduce the dosing interval for infliximab.
Objectives The purposes of this study are to compare drug survival between etanercept, infliximab and adalimumab when used with or without concomitant methotrexate, to compare dosing pattern and safety profile between these three agents in RA patients from our more than 12 years clinical experience.
Methods A total 297 RA patients treated with etancercept, infliximab or adalimumab for a minimum of three months were included in this retrospective cohort study conducted from 1999 to December 2012. All required variables were collected from our electronic medical records (EMR) and paper charts. Drug survival was compared between these three TNF-α inhibitors with or without use of concomitant methotrexate by Kaplan-Meier plots. Box-plot analysis was carried out to understand dosing pattern of infliximab in the form of initial maintenance dose and any dose escalation.
Results 183 etanercept, 60 infliximab and 54 adalimumab treated RA patients were included in this analysis. 75.4% etanercept treated patients remained on treatment whereas 51.7% and 48.1% in infliximab and adalimumab group respectively remained on treatment at the study conclusion. Secondary failures were reported 38.9%, 28.3% and 18.6% in adalimumab, infliximab and etanercept group respectively. Median drug survival rate of etanercept was higher compared to infliximab (43 months) and adalimumab (46 months) when used with concomitant methotrexate and infliximab (15 months), adalimumab (23 months) when used without concomitant methotrexate. 40% patients in the infliximab group required dose escalation to 5.31±1.38 mg/kg. Of these, majority (73.3%) patients required infliximab at every 6 week intervals.
Conclusions In this study of real-world clinical practice, etanercept had the longest drug survival rate. Infliximab had the lowest drug durability. Further, we also confirmed lower drug survival of infliximab and adalimumab when used without methotrexate. Majority of infliximab patients beginning treatment with infliximab had their frequency of infusions and/or dose increased within the first 12 months. These three drugs didn’t report any unexpected safety concerns.
Disclosure of Interest A. Chow Grant/research support from: Abbot, Amgen, BMS, Janssen, Lilly, Roche, E. Soucy: None Declared, A. Shah: None Declared, M. Got: None Declared