Objective: To analyze the long-term survival of subcutaneous biosimilar tumor necrosis factor inhibitors compared to the originator molecules in patients with rheumatic diseases, as well as the factors associated with drug discontinuation.
Methods: Retrospective analysis of BIOBADASER, the Spanish multicenter prospective registry of patients with rheumatic disease receiving biologic and targeted disease-modifying antirheumatic drugs. Patients who started etanercept (ETN) or adalimumab (ADA) from January 2016 to October 2023 were included. The survival probabilities of biosimilars and originators were compared using Kaplan-Meier estimating curves. To identify factors associated with differences in the retention rates, hazard ratios (HR) were estimated using Cox regression models for all and specific causes (inefficacy or adverse events [AEs]) of discontinuation.
Results: A total of 4162 patients received 4723 treatment courses (2991 courses of ADA and 1732 courses of ETN), of which 722 (15.29%) were with originator molecules and 4001 (84.71%) were with biosimilars. The originators were more frequently discontinued than biosimilars (53.32% vs 33.37%, respectively). The main reason for discontinuation was inefficacy (60.35% of the treatments). The risk of overall discontinuation was lower for biosimilars (adjusted HR 0.84, 95% CI 0.75-0.95). Female sex, obesity, and second or later treatment lines increased the risk of discontinuation, whereas disease duration and the use of concomitant methotrexate were associated with a greater survival. When assessing cause-specific reasons of discontinuation, excluding nonmedical switching, the results from the crude and adjusted analyses showed no significant differences in the retention rate between biosimilars and originators.
Conclusion: No significant differences were found between treatments in long-term survival due to inefficacy or AEs.
Keywords: biologic therapy; pediatric rheumatic diseases; rheumatoid arthritis; spondyloarthropathy.
Copyright © 2024 by the Journal of Rheumatology.