Real-World Study: No Increase in Health Resource Costs After Infliximab Biosimilar Introduction

Although biosimilars reduce drug purchasing costs for hospitals, it’s unclear whether those savings might be offset by increased health resource utilization following a non-medical switching initiative, according to the authors of a study of the introduction of the infliximab biosimilar CT-P13 in a single hospital in Switzerland. They found no differences in outpatient costs, inpatient costs, and length of hospital stays associated with introduction of the biosimilar.

The economic impact of non-medical switching is “subject to debate,” the authors said, as many economic evaluations have focused on drug purchase prices alone and have not considered health resource utilization. Costs associated with training medical staff, additional laboratory tests, administrative procedures, potentially switching back to another biologic, additional outpatient visits, and hospital stays may reduce the cost savings from the purchase price of the drug.

Infliximab, a monoclonal antibody targeting tumor necrosis factor (TNF)-α, is used to treat immune-mediated inflammatory diseases. CT-P13 was approved by the European Medicines Agency in 2013 and entered the market in Switzerland in 2016. The retrospective cohort study assessed health care expenditures in Swiss francs (CHF) of patients treated with the reference infliximab or the biosimilar CT-P13, based on outpatient costs, inpatient costs, and length of inpatient stays. Patients with inflammatory autoimmune diseases who were part of a previous retrospective study on reasons for discontinuation of CT-P13 were enrolled from a university hospital in Western Switzerland.

There were seven cohorts including 60 patients in immuno-allergology, 84 in rheumatology and 114 in gastroenterology:

1. Started therapy with the reference infliximab and maintained
2. Started therapy with CT-P13 and maintained
3. Started then discontinued reference product
4. Started then discontinued CT-P13
5. Switched from reference product to CT-P13 and maintained CT-P13
6. Switched from reference product to CT-P13 and discontinued CT-P13
7. Switched from reference product to CT-P13 and back to the reference product

The authors noted a few differences in patient characteristics between cohorts: patients who switched to CT-P13 and back to the originator were older (mean, 54 years) than those who started and discontinued the originator (mean, 34) and patients who started and discontinued CT-P13 (mean, 36). Also there was a higher proportion of female patients in the cohort that started and discontinued the reference product compared to the group that switched from the reference product to CT-P13 and maintained CT-P13.

Overall, inpatient costs were CHF 1,611 (SD, 1,020) per hospital day and outpatient costs were CHF 4,991 (SD, 6,931) per infusion, and the length of stay was 20 (SD, 28) days.

Because of the small sample size, the investigators used bootstrap analyses to compare outpatient and inpatient costs between cohorts: Patients who started and maintained CT-P13 and those who switched from the reference product to CT-P13 and then discontinued CT-P13 had lower mean costs per infusion than patients who switched from the reference product to CT-P13 and maintained CT-P13 and those who switched from the reference product to CT-P13 and back to the reference product. For inpatient costs, the patients who started then discontinued CT-P13 had a lower mean cost per hospital day than those who started and maintained the reference product.

The authors reported that multivariable analysis showed differences in both outpatient and inpatient costs by disease category, with rheumatology patients having higher mean cost per infusion than patients in gastroenterology or immuno-allergology. Patients in rheumatology and immuno-allergology had higher mean costs per inpatient hospital day than patients in gastroenterology. However, the authors noted that age was positively associated with costs, and patients in gastroenterology tended to be younger in their cohorts.

Length of stay was significantly different between some cohorts: patients who started then discontinued CT-P13 had shorter hospital stays compared to those who started then discontinued the reference product and those who started and maintained CT-P13.

The authors concluded that the introduction of CT-P13 in this hospital and any associated disruption of treatment management were not associated with differences in average outpatient costs, inpatient costs, or length of stay. They called for further research to evaluate the cost-effectiveness and benefits to patients associated with non-medical switching policies.

Reference

Krstic M, Devaud JC, Sadeghipour F, Marti J. Does the introduction of an infliximab biosimilar always result in savings for hospitals? A descriptive study using real-world data. Health Econ Rev. 2024;14(1):31. doi:10.1186/s13561-024-00507-5