Inflammatory bowel disease consists of either ulcerative colitis (UC) or Crohn's disease (CD).

The main aim of this study is to describe real-world treatment patterns in adults with moderate to severe ulcerative colitis or Crohn's disease when treated with vedolizumab. This will include the administration choices which can either be an infusion through a vein (intravenous or IV), or an injection just under the skin (subcutaneous injection, or SC).

Treatment will be determined by the study doctor according to routine clinical practice.

This is a non-interventional, prospective study of participants with IBD who initiated or who are currently ongoing induction or maintenance with vedolizumab in the real world setting.

The study will enroll approximately 120 participants. The data will be collected prospectively at the study sites and will be recorded into electronic case report forms (e-CRFs). All the participants will be assigned to a single observational cohort:

• Participants with IBD

This multi-center study will be conducted in Croatia and Slovenia having specialized gastroenterology centers. The overall duration of the study will be at least 26 months. Data will be collected at baseline, at 3 months (+/- 1 month) after induction, and every 6 months (+/- 1 month) after that, and at the time of switch, discontinuation and/or at routine follow-up visits up to 12 months.

Inclusion Criteria:

1. Has moderately to severely active IBD (UC or CD), initiating or ongoing IV induction treatment with vedolizumab in accordance with the current SmPC at baseline OR IBD participants receiving ongoing/maintenance IV vedolizumab treatment, with the option to switch to SC vedolizumab maintenance treatment.

Exclusion Criteria:

1. Prior history of intolerability, hypersensitivity, or other contraindications (active severe infections such as tuberculosis, sepsis, cytomegalovirus, listeriosis, and opportunistic infections such as Progressive Multifocal Leukoencephalopathy) to vedolizumab therapy as defined in the current SmPC.
2. Current or planned participation in an interventional clinical trial for CD or UC.
3. Cognitive incapacity, unwillingness or language barriers precluding adequate understanding or cooperation.

Adult participants with moderately to severely active UC or CD receiving vedolizumab treatment in accordance with the approved SmPC.

Takeda provides access to the de-identified individual participant data (IPD) for eligible studies to aid qualified researchers in addressing legitimate scientific objectives (Takeda's data sharing commitment is available on https://clinicaltrials.takeda.com/takedas-commitment?commitment=5). These IPDs will be provided in a secure research environment following approval of a data sharing request, and under the terms of a data sharing agreement.

IPD from eligible studies will be shared with qualified researchers according to the criteria and process described on https://vivli.org/ourmember/takeda/. For approved requests, the researchers will be provided access to anonymized data (to respect patient privacy in line with applicable laws and regulations) and with information necessary to address the research objectives under the terms of a data sharing agreement.