Evaluation of the Acceptability and Therapeutic Maintenance After Substitution of Ustekinumab With a Biosimilar

Inclusion Criteria: * Patient aged 18 years or older * Patient who has agreed to participate in the study and does not oppose the use of their health data * Patient with moderate to severe Crohn's disease treated with Stelara® in a pre-filled syringe according to the summary of product characteristics (SPC) with intervals of 8 or 12 weeks between injections * Patients presenting at least one of the following objective criteria: o PCR \< 5 mg/l o Calprotectin \< 250 μg/g o Harvey-Bradshaw index \< 5 * Patient in stable remission (defined by a stable ustekinumab dosage over the last 24 weeks and absence of corticosteroids for at least 3 months)• Patient for whom the investigator physician, prior to inclusion, has decided with their agreement, to replace Stelara® with Uzpruvo® * Patient having internet access enabling them to complete online questionnaires Exclusion Criteria: * Patient treated with ustekinumab with intervals between injections less than 8 weeks * Patients treated with ustekinumab in a pre-filled pen * Patient included in an interventional clinical trial at the time of inclusion * Patient refusing or unable to comply with the study follow-up procedures (patient unreachable by phone, unable to fill out the self-questionnaire or poorly speaking French...) * Patient under legal protection, under guardianship or under curatorship.