Introduction: As two biological agents, infliximab (IFX) and biosimilar adalimumab (CinnoRA®) are routinely used in the clinical management of ulcerative colitis (UC) in Iran. Objectives: This study was done to evaluate the cost-effectiveness of IFX versus CinnoRA for the treatment of moderate-to-severe UC patients.

Patients and Methods: To accomplish this, we developed a hybrid decision-tree/microsimulation (MS) approach for modeling UC’s natural history. We populated our model with available data on probabilities, costs, utilities / disutilities, and emergent adverse effects. Costs were reported in Iranian Rial (IRR) and in April 2021 US dollars ($). One-way and multiple sensitivity analyses were used to determine the uncertainty of the model’s parameters.

Results: For five, 10, and lifetime horizon times, patients on IFX received slightly more quality-adjusted lifeyear (QALY) per year in remission and experienced about 3 to 5 times less surgery than CinnoRA patients. With willingness-to-pay (WTP) thresholds of 1800 ($7826.08), 820($3565.21), and 520 ($2260.86) million IRR for these horizon times, IFX was cost-effective with 100% certainty. Our findings were highly sensitive to the number of adverse effects.

Conclusion: Our results demonstrated that IFX is more effective and more costly than CinnoRA, and if we ignore the predicted surgeries, CinnoRA is nearly as effective as IFX. However, these findings should be cautiously interpreted without a robust clinical trial of CinnoRA in UC patients. Since the impact of CinnoRA may have been over/underestimated.