Cost-Utility Analysis of Infliximab Biosimilars for Ankylosing Spondylitis in Germany

Abstract

Objectives Tumour necrosis factor α (TNFα) inhibitors are the best-selling drugs in the German Statutory Health Insurance system. While pharmaceutical expenditure is high for TNFα inhibitors, they have shown superior efficacy for rheumatic diseases. Superior efficacy leads to sustained ability to work and can prevent surgical intervention. The approval of biosimilars could lead to cost savings in pharmaceutical expenditure. The objective of our research was to set up a simulation model to evaluate the cost-effectiveness of biosimilar therapy in ankylosing spondylitis and to examine the cost-effectiveness of the biosimilar drug Inflectra ® vs. the originator Infliximab Remicade ®. Methods We developed an individual patient sampling model to simulate 10,000 virtual patients over their lifetime. Patients received either Remicade ® or Inflectra ®. After each 6-month cycle, therapy was evaluated. Improvement of functional status (BASFI) was recorded, converted to quality of life, and compared to natural progression. For each simulated patient, quality-adjusted life years (QALYs) and both direct and indirect costs were recorded. Results On average, patients gained 4.61 QALYs with Remicade ® vs. 4.86 QALYs with Inflectra ®. Direct costs excluding German mandatory rebates and value-added tax amounted to EUR 96,407.67 for Remicade ® vs. EUR 77,194.65 for Inflectra ®. Indirect costs were EUR 440,972.54 vs. EUR 439,314.28 over a patient's lifetime. Total costs were EUR 537,380.21 vs. EUR 516,508.93 excluding mandatory rebates and value-added tax. The incremental cost-utility ratio was negative for Inflectra ®, i. e., patients gained more QALYs at lower total costs. Sensitivity analysis shows the robustness of the results when altering time on treatment, natural progression, mortality rate, time on treatment with nonsteroidal anti-inflammatory drugs and inflation rate. Conclusion Our health economic model simulates clinical outcomes and costs of different treatments over the whole lifetime of 10,000 virtual patients. The simulation's results show potential savings achieved by the use of the infliximab biosimilar Inflectra ® compared with the originator Remicade ®. On average, the use of the biosimilar Inflectra ® lowers direct costs by EUR 23,573.55. For an international comparison of the results, we also report costs excluding German mandatory rebates and value-added tax. In this case, savings amount to EUR 19,213.02. The approval of biosimilars for the best-selling TNFα inhibitors adalimumab and etanercept has the potential to lower direct medication costs for inflammatory rheumatic diseases. However, clinical trials are required to prove equivalence in efficacy and a comparable side-effect profile for biosimilars.