OBJECTIVES: After the approval of infliximab biosimilars, expenditure for Remicade® decreased by 4.3 % in 2015 in Germany. Total infliximab expenditure including biosimilars accounted for € 231.77mn in Statutory Health Insurance (SHI) pharmaceutical costs. Potential savings of Remicade® substitution by biosimilars was estimated at € 46.51mn per year for Germany. We aim to implement a method to examine the cost-effectiveness of biosimilars for patients with ankylosing spondylitis (AS). We analyze the cost-effectiveness of biosimilar Inflectra® vs. Remicade® for the German SHI system.

METHODS: We simulate 10,000 hypothetical AS patients by setting up an individual patient sampling lifetime model. Initial characteristics are derived from clinical studies. Direct and indirect costs are incorporated to reflect a societal perspective. After each 6-month cycle, discontinuation of treatment due to adverse events or loss of efficacy is evaluated. As outcome measure, improvement of functional status (BASFI) is recorded, converted to quality of life, and compared to mean natural progression. Incremental quality-adjusted life years (QALYs) are calculated.

RESULTS: Direct costs excluding value-added tax and mandatory rebates are € 77,194.65 for Inflectra® vs. € 96,407.67 for Remicade®. Indirect costs are € 439,314.28 vs. € 440,972.54. Total costs excluding value-added tax and mandatory rebates are € 516,508.93 for Inflectra® vs. € 537,380.21 for Remicade®. Patients gain 4.86 QALYs with Inflectra® and 4.61 QALYs with Remicade®. The incremental cost-utility ratio is negative for the biosimilar, i.e. patients gain more QALYs at lower total costs. Sensitivity analysis shows the results' robustness when altering mortality rates, disease progression, time on treatment with nonsteroidal anti-inflammatory drugs and overall time on treatment.

CONCLUSIONS: Treatment of AS with biosimilar Inflectra® is cost-effective compared with Remicade® treatment. Inflectra® lowers total costs from a societal perspective. To capture the whole range of the treatments' economic effects, estimation of cost-effectiveness relies on simulation with a lifetime horizon.