Determinants of biological drug survival in rheumatoid arthritis: evidence from a Hungarian rheumatology center over 8 years of retrospective data

OBJECTIVE: To compare drug survival of biological therapies in patients with rheumatoid arthritis (RA), and analyze the determinants of discontinuation probabilities and switches to other biological therapies. MATERIALS AND METHODS: Consecutive RA patients initiating first biological treatment in one rheumatology center between 2006 and 2013 were included. Log-rank test was used to analyze the differences between the survival curves of different biological drugs. Cox regression was applied to analyze the discontinuation due to inefficacy, the occurrence of adverse events, or to any reasons. RESULTS: A total of 540 patients were included in the analysis. The most frequently used first-line biological treatments were infliximab (N=176, 33%), adalimumab (N=150, 28%), and etanercept (N=132, 24%). Discontinuation of first tumor necrosis factor-alpha (TNF-α) treatment was observed for 347 (64%) patients, due to inefficacy (n=209, 60%), adverse events (n=103, 30%), and other reasons (n=35, 10%). Drug survival rates for TNF-α and non-TNF-α therapies were significantly different, and were in favor of non-TNF-α therapies. Every additional number of treatment significantly increased the risk of inefficacy by 27% (p<0.001) and of adverse events by 35% (p=0.002). After the discontinuation of the initial TNF-α treatment, switching to rituximab and tocilizumab was associated with significantly longer treatment duration than switching to a second TNF-α. The non-TNF-α therapies resulted in significantly longer treatment duration, due to both less adverse events and longer maintenance of effectiveness. CONCLUSION: Non-TNF-α therapies resulted in significantly longer treatment duration, and lost their effectiveness later. Increase in the number of switches significantly increased the risk of discontinuation of any biological therapy.