The CROCO Study: CROhn's Disease COhort Study

Therefore, the investigators designed a prospective, multicentre, study of the clinical course, anatomical progression and treatment of newly diagnosed CD and plan to include 600 patients over a 2-year period. Patients will be followed over 5 years after diagnosis (the date of diagnosis will be the date of the index histopathology describing CD; in special situations where pathology is not available the date of diagnosis will be the date that CD was declared by the physician). A morphological evaluation (LI), using abdominal magnetic resonance, will be performed at 1, 3 and 5 years after diagnosis. Ileocolonoscopy, upper endoscopy and/or pelvic MRI will be included according to disease location. Patients will be treated with standard of care therapy and will be followed for 5 years after diagnosis, with semestrial visits after the Year 1 (LI 1). At each visit, clinical and laboratory markers will be collected. Perianal and abdominal surgeries during follow-up will be registered. The disability index questionnaire will also be recorded every year.

A preliminary requisite is therefore to implement and standardize examination reports and damage definitions used to calculate the LI. To this end, training session, supervised by members of the steering committee, will be held for participating gastroenterologist and radiologists. Based on commented ileocolonoscopy, upper endoscopy abdominal MRI and pelvic MRI, these sessions will highlight how lesions should be characterized and graded accordingly to implement the Lémann Index.