TDM Guided Early Optimization of ADAL in Crohn's Disease

Eligibility Details: Inclusion Criteria: - Age 18 or older. - Crohn's disease diagnosed based on standard objective methodology (clinical, biochemical, endoscopic, histological and radiological correlation). - Active disease based on Harvey Bradshaw Index (HBI >5) and elevated C-reactive protein (CRP) (>normal reference range for local laboratory) OR fecal calprotectin (FCP) (>250 µg/g) - Due to commence treatment with ADAL. Exclusion Criteria: - Severe co-existing cardiopulmonary, hepatic, renal, neurologic, or rheumatologic disease. - History of active HIV, hepatitis B or C infection, - Patients with ileostomy/colostomy, ileal-pouch anal anastomosis or severe perianal fistulising disease. - Pregnancy - Prior exposure to ADAL