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.