Inpatient Infliximab Biosimilar Cost-Savings: Cost Analysis of Inpatient Treatment with Originator Infliximab (Remicade™) versus Biosimilar Infliximab (Renflexis™) for Acute Severe Ulcerative Colitis.

Introduction: Infliximab (IFX) is a standard, inpatient salvage therapy for the treatment of refractory acute severe ulcerative colitis (ASUC). Remicade™ is the originator IFX. Its biosimilar Renflexis™ offers a reduced cost structure. We performed a cost-minimization analysis to compare costs with Remicade™ and Renflexis™ for the inpatient treatment of ASUC.

Methods: Retrospective clinical and financial data were obtained from 34 inpatients with refractory ASUC who received Renflexis™ (n = 17) or Remicade™ (n = 17) between 2019 and 2021. Clinical data included admission and discharge laboratory values. Financial data included a decision support drug cost (DSDC), constituting the total cost associated with inpatient IFX administration, and total inpatient cost of care. The following equation generated a ratio (rDSDC) representing the percentage of drug cost (or DSDC) of the total inpatient cost of care, after controlling for IFX dose and length of stay: [DSDC of IFX/Number of Units of IFX] ÷ [Total Inpatient Cost of Care/Length of Stay in Days]. Median and non-parametric Wilcoxon ranked sum test were used for analyzing patient demographics, clinical, and financial data.

Results: No differences were found in baseline or discharge clinical parameters. The median unadjusted ratio of DSDC to total inpatient cost of care was 0.387 versus 0.241 in the Remicade™ versus Renflexis™ groups (p = 0.0025), respectively, representing an absolute difference of ∼14%. Median adjusted rDSDC were 0.04 versus 0.024 in the Remicade™ versus Renflexis™ groups, respectively, representing a relative cost reduction of ∼40% (p = 0.0001).

Discussion: The unadjusted absolute cost reduction and adjusted relative cost reduction were, respectively, 14% and 40% in the Renflexis™ group as compared to Remicade™, when treating inpatient ASUC. Our calculation included median DSDC as a percentage of the total inpatient cost of care, controlling for IFX dose and length of stay. This reduced cost structure promotes use of Renflexis™ for ASUC inpatients and may reduce costs systemically.