A Study to Assess Real-world Outcomes for Long-Term Use of Guselkumab

Inclusion Criteria: * Must be eligible for biologic treatment and initiate guselkumab according to the approved indications as described in the current version of the summary of product characteristics (SmPC) of drug. Decision to prescribe must solely be made by the treating physician. Enrolment must take place before or on the day of the first administration (but after treatment decision by physician) * Must have confirmed diagnosis of moderate-to-severe UC or CD disease record in their medical records * Must sign a participation agreement/Informed consent form (ICF) allowing source data verification in accordance with local requirements Exclusion criteria: * Contraindicated to guselkumab per the label * Is currently enrolled in an interventional clinical study * Has been previously exposed to Interleukin (IL)-23 inhibitors, including tremfya (guselkumab), skyrizi (risankizumab) and omvoh (mirikizumab). As an exception, participants with history of ustekinumab exposure may be included * History of more than 4 lines of advanced inflammatory bowel disease (IBD) therapy (biologics and/or small molecules) * Is unable to provide informed consent