Background: The first biosimilar (BS) of infliximab (IFX) was approved for the same indications as the biological reference in inflammatory bowel disease (IBS). After its commercialization we have results of efficacy and safety in IBD, however, data on the switch to BS are still limited. On the other hand, economic impact studies are needed in real life.
We aimed to evaluate the efficacy and safety of the switch BS in patients with IBD in clinical practice and analyze the economic impact of this strategy.
Methods: Observational and retrospective study. All the patients of the monographic consultation of IBD in maintenance treatment with IFX at the time of introduction of the BS were included. The clinical activity at the time of change to BS, at 6 and 12 months was analyzed using the Harvey Bradshaw index for Crohn's disease (EC) and partial Mayo score for ulcerative colitis (UC). Adverse effects, flares, intensification or withdrawal of treatment were recorded. The total amount in milligrams of IFX administered per patient was calculated and the milligram drug price was established based on the real sales price of the original IFX and BS vial.
Results: We included 72 patients (62 EC/10 CU; 47% male; mean age of 46 years (±13 years). The mean time to treatment with baseline IFX before switching to BS was 51 months (±38.83 months). At the time of the switch, 86% of the patients were in clinical remission (62/72), with remission at 12 months maintaining 80.5% (58/72). Nine patients required treatment with steroids, 10 needed intensification and 8 urgent surgery (4 laparatomy and 4 perianal disease). Treatment was withdrawn in 9,72% of the patients (7/72), in 4 of them due to loss of secondary response. Adverse effects were recorded in 10 patients, 13,8% (mostly infections), without any withdrawal or treatment modification. A mean of 2780mg (DS 1092.29) of BS per patient was administered during one year, the total cost was 746150 € gross, which meant a saving of 248716 € gross annuals compared to the estimated expenditure with IFX before being marketed BS.
Conclusions: The switch to BS in IBD is effective in maintaining clinical remission at 12 months. No relevant adverse effects have been reported during the study period, one year. This strategy supposes a relevant reduction in the annual pharmaceutical expenditure in IBD patients.