Treatment Persistence in Rheumatoid Arthritis Before and After Etanercept Biosimilar Introduction: A Nationwide...

Australia has one of the highest rates of rheumatoid arthritis (RA) worldwide. Etanercept, a widely used biologic for severe RA, has had a publicly subsidised biosimilar available in Australia since 2017. However, real-world data on how biosimilar availability has affected treatment patterns remain limited.

This study aimed to assess treatment persistence-a surrogate measure of long-term treatment effectiveness-with etanercept before and after public subsidy of its biosimilar for RA, utilising a national sample.

This retrospective cohort study analysed national healthcare claims data from the Pharmaceutical Benefits Scheme (PBS) via the Australian Bureau of Statistics DataLab. Adults (age ≥ 18 years) initiating etanercept for severe RA were stratified into two cohorts: historical (before biosimilar PBS listing, comprising only originator users) and contemporary (after biosimilar PBS listing, comprising both biosimilar and originator users). Kaplan-Meier analysis and multivariate Cox regression were employed to assess treatment persistence. Subgroup analysis of older adults and sensitivity analysis limited to biologic-naïve individuals were also performed.

A total of 10,234 individuals initiating etanercept for severe RA were included, with 4461 in the historical cohort and 5773 in the contemporary cohort. The median time to treatment discontinuation was 10.0 months (95% confidence interval (CI) 9.7-10.6) in the contemporary cohort and 10.6 months (95% CI 10.0-11.4) in the historical cohort (p = 0.08). At 12 and 24 months, treatment retention rates were similar between cohorts. The adjusted hazard ratio for treatment discontinuation in the contemporary cohort was 1.00 (95% CI 0.96-1.05), indicating no significant differences. Subgroup and sensitivity analyses yielded similar results.

This large, population-based study found no significant difference in treatment persistence following the introduction of the etanercept biosimilar in Australia. These findings support the real-world integration of biosimilars into routine care. Further research should include direct comparative analyses of originator and biosimilars to inform long-term treatment strategies, clinician confidence, and sustainable healthcare policy.