The primary aim of this study is to explore the time course of response to Vedolizumab in participants with CD as measured by the Patient-Reported Outcomes Measurement Information System (PROMIS) Pain Interference-short form (SF), as well as other PROMIS domain SFs (fatigue, anxiety, depression, sleep disturbance, physical function, and ability to participate in social roles and activities); other PRO measures will also be assessed.

Vedolizumab (VDZ), a monoclonal antibody that selectively targets intestinal T-cell trafficking, is an effective and safe treatment for moderately to severely active Crohn's disease (CD). Recent evidence from open-label, blinded endpoint studies such as VERSIFY and LOVE-CD provide further support for the efficacy of VDZ in achieving clinical, endoscopic, histologic and radiologic disease improvement in CD. Despite these data, VDZ is generally perceived to have a slower onset of action than other biologics, including tumor necrosis factor (TNF) antagonists and the interleukin (IL)-12/23 antagonist, ustekinumab (UST). The IL-23 antagonist risankizumab (RISA) has been more recently approved for treatment of CD and post-hoc analyses of SEQUENCE trial data showed RISA to be superior to UST for inducing clinical remission at Week 24, and thus, RISA may also be considered to have a quicker onset of action than VDZ. This perception largely emanates from the results of the VDZ pivotal for CD (GEMINI 2) where efficacy was assessed at Week 6 after only 2 doses in a largely refractory population. However, in clinical practice VDZ induction consists of 3 doses of VDZ 300 mg administered intravenously at weeks 0, 2 and 6 instead of the 2 doses used in the pivotal trials. In recent clinical trials, induction endpoints for therapeutics in CD are now typically measured at least after Week 12. Accordingly, it is uncertain whether the generally held perception of a relatively slow onset of action for VDZ is accurate. Moreover, it should also be noted that the perception of a slow onset of action has also been conflated to infer that VDZ is a relatively less effective induction therapy in CD than TNF antagonists or UST. Further data to evaluate these issues are needed.

Rapidity of symptom resolution, which is commonly used as a surrogate for speed of onset, is a priority for patients and clinicians. It is therefore important to better understand the kinetics of symptom improvement captured using patient-reported outcomes (PROs) in patients initiating VDZ for treatment of CD.

Inclusion Criteria:

1. Participant is an adult 18 years of age or older with confirmed CD, as per standard clinical criteria which may include symptoms, endoscopy, histopathology, and imaging.

2. Participant has active CD and has been prescribed as standard of care (SOC) and is planned to start VDZ or IL-23 antagonist therapy (UST, RISA, or GUS or MIR [if approved for the treatment of CD during the recruitment period for this study]) for the first time in accordance with the product label, as determined by the treating physician.

3. Participant has a baseline PROMIS Pain Interference-SF score ≥ 15 (corresponding T-score ≥ 55) (PROMIS Pain Interference-SF 8a [V1.1]).

   a. Score is calculated by adding score (1 to 5) for each of the 8 subcomponents.

4. Participant has completed all SOC biologic work-up assessments (this may include assessment of tuberculosis, chronic infections, Clostridioides difficile infection and vaccination status per local practice).

5. Ability of participant to participate fully in all aspects of this observational study. Full comprehension of consent language and informed consent must be obtained from the participant and documented.

Exclusion Criteria:

1. Participant has CD-related surgery planned or anticipated during the study.

2. Participant has prior exposure to an advanced therapy for the treatment of CD (biologic or small molecule) other than an anti-TNF (i.e., anti-integrin, anti-IL, Janus kinase inhibitors, or sphingosine-1-phosphate receptor 1). Prior failure or intolerance to 2 or more anti-TNF (i.e., infliximab, adalimumab, or certolizumab pegol) therapies in the past 3 years is also cause for exclusion.

3. Participant has an active infection at baseline requiring intravenous systemic antibiotics.

   Note: The treating physician must have completed all appropriate baseline screening tests as per the product label.

4. Participant has evidence of C. difficile toxin or is prescribed treatment for C. difficile infection, or other intestinal bacterial pathogen, ≤ 2 weeks prior to Screening.

5. Participant has chronic non-inflammatory bowel disease pain.

This study will be conducted in US and Canadian participants with CD prescribed VDZ or IL-23 antagonists for the first time. Approximately 300 participants with CD who are initiating first-time treatment with VDZ or UIL-23 antagonists will be enrolled in this study.