The ISI is used to evaluate the severity of insomnia in patients, primarily evaluating sleep problems over the past two weeks and their impact on quality of life. The scale consists of seven items, each rated on a 5-point scale (0 = none, 4 = very severe), with a total score ranging from 0 to 28. Higher scores indicate more severe insomnia, where 0-7 points indicate no clinically significant insomnia, 8-14 points indicate subthreshold insomnia, 15-21 points indicate moderate clinical insomnia, and 22-28 points indicate severe clinical insomnia.

The FFS is a brief self-rated questionnaire specifically designed to assess daytime fatigue associated with insomnia, commonly used for rapid screening of patients' fatigue levels. The scale comprises 7 items, primarily measuring fatigue characteristics over the past two weeks. The first six items are scored from 0 (not at all) to 4 (extremely severe), while the time period item is scored based on the number of time periods checked (1 point per time period). All item scores are summed to obtain the total score, which typically ranges from 0 to 31, with higher scores indicating greater severity of fatigue.

The GAD-7 is used to evaluate the symptoms and severity of anxiety in patients. It includes 7 entries, each with a score of 0 to 3 and a total score between 0 and 21. Higher scores indicate greater anxiety severity. The commonly used classification criteria are as follows: 0-4 points (no or minimal anxiety), 5-9 points (mild anxiety), 10-14 points (moderate anxiety), and 15-21 points (severe anxiety). A total score of 10 or higher is generally indicated the possible presence of an anxiety disorder.

The PHQ-9 is used to assess the symptoms and severity of depression in patients. It consists of nine main entries, each with a score of 0 to 3 and a total score between 0 and 27. The score is generally used to determine the severity of depression: 0-4 points indicate no depression, 5-9 points indicate mild depression, 10-14 points indicate moderate depression, 15-19 points indicate moderately severe depression, and 20 or higher points indicate severe depression.

All patients will undergo measurement of drug trough concentrations for IFX and VDZ at Week 14 of treatment. The concentration testing will be performed within 24 hours prior to the next scheduled infusion (i.e., close to the time of drug administration).

FC is a widely used biomarker in the assessment and management of iIBD. As a stable protein released by activated neutrophils during intestinal inflammation, FC can effectively reflect the degree of mucosal inflammation non-invasively; elevated FC levels correlate with active intestinal inflammation, helping to distinguish between inflammatory bowel disease and functional gastrointestinal disorders such as irritable bowel syndrome. It also plays an important role in monitoring disease activity, evaluating treatment response, detecting early mucosal recurrence, and supporting clinical decision-making in patients with IBD.