Objective: The market entry of biosimilars is expected to bring budgetary relief. Our objective was to determine how the introduction of biosimilars influences medication costs in patients with rheumatoid arthritis (RA) and which patients gain access to biologics due to the availability of biosimilars.
Methods: Using hospital data of patients with RA between 2014 and 2018, an interrupted time series was performed. The interruption in the time series was placed at June 2016 (i.e., the introduction of the etanercept biosimilar). The changes in trends for rheumatic medication costs before and after the interruption were measured. Secondary analyses focused on explaining these trends.
Results: In the first quarter after the interruption, there was a decrease in total costs for biologic users of -€63,020 (95% CI -€96,487 to -€29,553, P = 0.001). The postinterruption trend did not differ from the preinterruption trend (95% CI -€6695 to €6715, P = 0.998) and after 3 quarters, the medication costs were back at the interruption level. After the interruption, the average cost per biologic user decreased by -€370 (95% CI -€602 to -€138, P = 0.005), followed by a quarterly decrease (relative to the preinterruption trend; 95% CI -€86 to -€14, P = 0.010), bending the average cost curve. The percentage of patients being treated with biologics increased in postinterruption by 0.50 percentage points quarterly (95% CI 0.38-0.62, P < 0.001). Also, the average age at the start of the first biologic increased after the interruption (P = 0.057).
Conclusion: The average cost per patient treated with biologics decreased after the introduction of biosimilars with a persistent trend. However, the budgetary relief due to market entry of biosimilars vanished quickly due to an increase in patients treated with biologics.
Keywords: biologic therapy; biosimilars; cost savings; rheumatic diseases.
Copyright © 2021 by the Journal of Rheumatology.