A Cost-Utility Analysis of Switching from Reference to Biosimilar Infliximab Compared to Maintaining Reference Infliximab in Adult Patients with Crohn's Disease

Abstract

Background and aims: Lower-cost biosimilar infliximab may address affordability concerns in the treatment of adults with Crohn's disease (CD), however, evidence regarding the cost-effectiveness of switching from reference to biosimilar is warranted. The aim of this research was to assess the incremental cost of switching from treatment with reference infliximab to biosimilar compared with maintaining reference infliximab in adults with CD per quality-adjusted life year (QALY) gained.

Methods: A probabilistic cohort Markov model with 8-week cycle lengths was constructed to estimate the incremental costs and effects of switching over a 5-year time horizon from a public payer perspective. Base-case clinical inputs were obtained from NOR-SWITCH subgroup analyses and other published trials. Costs were obtained from Canadian sources. A total of 10,000 simulations were run. Sensitivity analysis was used to test the robustness of the results to variations in uncertain parameters.

Results: Switching to biosimilar infliximab was less costly but also less effective with incremental savings of $46,194 (95% confidence interval [CI]: $42,420, $50,455) and a loss in QALYs of -0.13 (95% CI: -0.16, -0.07). Eighty-three per cent of the simulations demonstrated incremental cost savings and an incremental loss of effectiveness. The model was sensitive to differences in rates of disease worsening between reference and biosimilar infliximab.

Conclusions: While biosimilar infliximab is associated with incremental savings for patients on maintenance therapy who are switched from reference infliximab, funding decision makers must decide whether a small loss of effectiveness is justified. Further evidence will help to inform reimbursement policy.

Keywords: Cost-utility analysis; Crohn’s disease; Infliximab.

Figure 1.

Model structure. The structure of the model is summarized in Figure 1. It is assumed that the patient enters the model and the treatment decision either requires the patient to continue maintenance therapy with reference infliximab or switch to treatment with biosimilar infliximab with identical dosing and administration. Patients then enter the Markov model and were distributed into one of two states: clinical remission or clinical response and move through the model as shown.

Figure 2.

Cost-effectiveness of biosimilar infliximab results. As shown in the figure, 83.67% of the iterations lie in the south-west quadrant (less costly and less effective) and 16.33% lie in the south-east quadrant (less costly and more effective). Those simulations that lie in the south-east quadrant imply that switching to biosimilar infliximab is a dominant strategy as it results in incremental cost-savings and an incremental gain in QALYs. The dashed line shows a decision-maker willingness to pay threshold of $50,000 which represents a maximum the decision maker may be willing to pay for one additional QALY.