Switching from intravenous to subcutaneous infliximab and vedolizumab in patients with inflammatory bowel disease: impact on trough levels, day hospital visits, and medical expenses.

Objective: Subcutaneous (SC) infliximab (IFX) and vedolizumab (VDZ) have recently become available. We aimed to examine the impact of switching from intravenous (IV) to SC IFX and VDZ in patients with inflammatory bowel disease (IBD) on costs, the day hospital burden, trough levels, and clinical outcomes.

Methods: Our study comprised the cohort of IBD patients receiving IV IFX or VDZ at our hospital in 2022. We evaluated costs, day hospital visits, trough levels, biochemical markers, relapse rates, and self-report outcomes until Jun 30 2023.

Results: Of 114 patients, 18 continued IV therapy, 80 were switched to SC therapy, and 16 were inductions. Eighty-eight (90%) remained in steroid-free remission with no difference between the IV or SC groups. The mean IFX trough level changed from 8.2 ± 4.5 µg/ml to 14.5 ± 5.9 µg/ml,  < 0.001, and the VDZ trough level from 14.7 ± 7.1 mg/ml to 26.5 ± 13.8 mg/ml,  < 0.001. The average yearly costs of infusions and injections per patient were 2 580 € and 7 482 € for IFX and 15 990 € and 13 101 € for VDZ. The annual reduction of day hospital visits was 6,9 per patient.

Conclusions: IV and SC IFX and VDZ are equally effective in maintaining remission in IBD, but SC administration reduces day hospital visits and results in higher trough levels. SC VDZ is less and SC IFX more expensive than IV therapy. Further studies are needed to assess optimal dosing and separate trough levels for SC therapy.