Subcutaneous Infliximab After A Previous Intravenous Dose Optimization

Inclusion Criteria: * Voluntary written informed consent of the participant or their legally authorized representative has been obtained prior to any Screening procedures. * Patients with a previously documented CD, UC, IBDU diagnosis confirmed by clinical, endoscopic, histological, and/or radiological criteria * Males and females ≥18 years old. * Patients must be in steroid-free clinical remission at Screening defined as a rectal bleeding score of 0 and a stool frequency score of ≤1 for patients with UC / IBDU, or an average daily abdominal pain score ≤1 and a liquid stool frequency score ≤2.8 for patients with CD (based on the 3 days before the screening visit, excluding the day of or the day before an eventual endoscopy with bowel preparation) and this without the need for any type of steroids in the previous eight weeks. * Patients must be in biological remission at screening defined as a CRP \<10 mg/L and a fecal calprotectin \<250 µg/g. * Patients receiving IV infliximab for at least 26 consecutive weeks. * Patients receiving a stable IV infliximab dosing schedule for at least 20 weeks. * Patients receiving an average IV infliximab dose per 8 weeks based on the two most recent IV administration of more than 8 mg/kg, but not more than 22 mg/kg * Patients who speak and read fluently Dutch, French or English. Exclusion Criteria: * Male or female ≤ 18 years * Patients with an ileorectal anastomosis, an ileal pouch-anal anastomosis or an ostomy * Patients participating in an interventional clinical trial with an Investigational Medicinal Product (IMP) or device * Patients previously treated with SC infliximab * Patients with active perianal fistulizing disease * Patients with microscopic colitis