A Real-World Study of Guselkumab Persistence and Effectiveness in Participants With Crohn's Disease or Ulcerative Colitis

Inclusion criteria: * Participant 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 the drug. Decision to prescribe must solely be made by the treating physician. Participant must have been at least 8 weeks under guselkumab treatment before being included in the study, regardless if they are still on guselkumab treatment or not * Participant must have a confirmed diagnosis of moderate-to-severe or Crohn's Disease (CD) or Ulcerative Colitis (UC) recorded in their medical records: Harvey-Bradshaw Index (HBI) greater than (\>)4 for CD and Partial Mayo Score (pMS)\>2 for UC * Participant \[and/or their legally-acceptable representative where applicable\] 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 * It 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 the ICF