The aim of this retrospective and prospective observational study is to investigate and compare the real-world effectiveness and safety of different dual-target combination therapies in patients with inflammatory bowel disease (IBD).

The key questions to be addressed are:

In patients with refractory IBD who receive either two biologic agents or one biologic agent plus one small molecule drug, what is the real-world effectiveness and safety of different combination regimens?

The researchers will conduct a retrospective analysis of medical records and electronic health data from patients diagnosed with IBD, and will enroll and document patients receiving combination advanced targeted therapy (CATT) for long-term follow-up. The treatments received by these patients are part of routine first-line clinical care or routine rescue clinical care. All treatment decisions were made by treating clinicians according to the standard of care; the investigator did not assign or modify any therapeutic interventions. Data will be collected during a defined follow-up period to compare the real-world effectiveness and safety profiles of different treatment exposure strategies.

This is a retrospective and prospective observational cohort study. All described interventions are part of routine clinical care for patients with inflammatory bowel disease (IBD). Treatment decisions were made by treating clinicians according to the standard of care; the investigator did not prospectively assign, modify, or control any therapeutic interventions. Participants did not receive any intervention specifically for the purpose of this study. The study only involves retrospective analysis of existing medical records to compare real-world outcomes between different treatment exposure patterns.

Inclusion Criteria:

1. Patients diagnosed with IBD;
2. Patients treated with Combined Advanced Targeted Therapy at 4 tertiary IBD centers in China from June 2023 to December 2026.
3. Patients with complete and available clinical, endoscopic, and follow-up data；
4. Patients for whom the study was approved by the Institutional Research 5.Ethics Committee and conducted in accordance with the Declaration of Helsinki.

Exclusion Criteria:

• 1.Patients with hemodynamic instability; 2.Patients with obvious liver and kidney function injury: bilirubin,aminotransferase (ALT, AST) exceeded the upper limit of normal by 2 times; eGFR < 60ml/min or dialysis patients; 3.Patients allergic to biologic agents or small molecule agents; 4.Patients whose primary disease was gastrointestinal malignancy; 5.Patients currently suffering from serious or uncontrolled underlying diseases of the blood, digestive tract, metabolism, endocrine, lung, heart, nervous system, mental system, etc.; 6.Female patients during pregnancy and breastfeeding (including patients with reproductive needs)； 7.Patients with current infection with infectious diseases (hepatitis B, hepatitis C, syphilis, AIDS, tuberculosis, etc.); 8.Patients with missing key data for outcome assessment; 9.Any other circumstances which, in the opinion of the investigator, would render the subject unfit for study inclusion.

This is a multicenter, retrospective and prospective cohort study conducted at 4 tertiary inflammatory bowel disease (IBD) centers in China from April 2023 to April 2026. A total of 117 patients with IBD were enrolled. All patients received Combined Advanced Targeted Therapy (either two biologic agents, or one biologic agent together with one small molecule agent).