Subcutaneous Infliximab After A Previous Intravenous Dose Optimization

The goal of this clinical trial is to learn about the treatment with subcutaneous infliximab in patients with inflammatory bowel disease (IBD) that were previously treated with an optimized dose of intravenous infliximab. The main question it aims to answer is: \- Is switching to a weekly dose of subcutaneous infliximab (120 mg) associated with a better outcome compared to the standard fortnightly administration of 120 mg subcutaneous infliximab in patients who received an optimized intravenous dosing schedule? Participants will switch from intravenous infliximab to subcutaneous infliximab and will be randomized to the intervention arm (Subcutaneous infliximab weekly) or the interventional comparison arm (subcutaneous infliximab bi-weekly). Participants will follow daily clinical practice in the monitoring for clinical and biological remission. The participants that are willing to switch to subcutaneous infliximab will be compared to a group of participants not willing to switch. These participants will continue to be treated with their optimized intravenous dose of infliximab.