Real-World Study of IL-23 Inhibitors in Active Crohn's Disease

The goal of this observational study is to learn about the effectiveness and safety of IL-23 inhibitors in adults with active Crohn's disease in real-world clinical practice. The main questions it aims to answer are: * What proportion of participants achieve clinical remission at Week 12 after starting treatment with an IL-23 inhibitor? * What are the clinical, endoscopic, biomarker, imaging, and safety outcomes during induction and maintenance treatment? This is not a head-to-head randomized study. Treatments are selected by treating physicians as part of routine clinical care. For a nested comparative analysis, bio-naive participants treated with IL-23 inhibitors will be compared with a concurrent prospective cohort of bio-naive participants treated with TNF inhibitors to evaluate comparative effectiveness and safety. Participants will: * Receive treatment chosen by their treating physicians as part of routine clinical care, including IL-23 inhibitors or TNF inhibitors * Attend study follow-up visits during induction and maintenance, including assessments at baseline, Week 12 and Week 52 * Undergo routine clinical evaluations, which may include symptom assessment, laboratory tests, endoscopy, and imaging, as available * Be monitored for adverse events and treatment changes during the study * Optionally provide blood, stool, and other available samples for exploratory biomarker, microbiome, metabolomic, and other multi-omics analyses related to treatment response

Inclusion Criteria: 1. Age 18 to 75 years 2. Diagnosis of Crohn's disease based on clinical presentation, endoscopy, imaging, and/or histopathology, consistent with ECCO criteria or Chinese IBD consensus criteria 3. Active Crohn's disease with a baseline Crohn's Disease Activity Index (CDAI) score of 150 to 450, and at least one of the following objective inflammatory findings: (1) Endoscopic activity within 1 month before enrollment, defined as Simple Endoscopic Score for Crohn's Disease (SES-CD) \>=6 for ileocolonic or colonic disease, or SES-CD \>=4 for isolated ileal disease, (2) Active intestinal inflammation on bowel ultrasound, computed tomography enterography (CTE), or magnetic resonance enterography (MRE), (3) Serum C-reactive protein (CRP) above the upper limit of normal, (4) Fecal calprotectin (FC) \>=250 ug/g 4. Planned initiation of IL-23 inhibitor therapy in routine clinical practice, including guselkumab or risankizumab, with no prior exposure to IL-23 inhibitors 5. Prior treatment history for the IL-23 inhibitor cohort may include biologic-naive or biologic-experienced patients; prior exposure to TNF inhibitors, vedolizumab, or ustekinumab is permitted 6. If receiving concomitant medications, doses should be stable for at least 2 to 4 weeks before enrollment, including oral corticosteroids, azathioprine, 6-mercaptopurine, methotrexate, or 5-aminosalicylic acid 7. Able to understand the study procedures, provide written informed consent, and comply with follow-up and biospecimen collection requirements 8. Additional criteria for the concurrent prospective TNF inhibitor cohort used in the nested comparative analysis: (1) Participants must be bio-naive, defined as no prior exposure to any biologic agent (including TNF inhibitors, vedolizumab, ustekinumab, etc.) or targeted small-molecule therapy (such as JAK inhibitors), (2) Participants must also meet Inclusion Criteria 1, 2, 3, 6, and 7 above, (3) Participants must be planned to initiate TNF inhibitor therapy in routine clinical practice Exclusion Criteria: 1. Prior exposure to any IL-23 inhibitor, including guselkumab, risankizumab, mirikizumab, or other IL-23-targeted agents 2. Diagnosis of inflammatory bowel disease other than Crohn's disease, or other intestinal disorders that may confound diagnosis, including ulcerative colitis, IBD-unclassified, intestinal tuberculosis, ischemic colitis, or radiation enteritis 3. Crohn's disease requiring urgent surgery or associated with severe complications, including active bowel perforation, uncontrolled fistula with severe infection, or complete bowel obstruction 4. Active infection or high-risk infectious condition, including active tuberculosis, latent tuberculosis without appropriate prophylaxis, active hepatitis B or C, HIV infection, or severe/recurrent infection history 5. Current or prior malignancy, except adequately treated non-melanoma skin cancer or cervical carcinoma in situ with no evidence of recurrence 6. Pregnancy, breastfeeding, or planned pregnancy during the study period 7. Severe systemic disease or other condition that, in the investigator's judgment, makes participation unsuitable, including severe cardiac, hepatic, or renal dysfunction, uncontrolled autoimmune disease, or psychiatric disease affecting adherence 8. Inability to complete follow-up, poor compliance, or recent participation in another interventional clinical trial