Guselkumab for Overlap Inflammatory Bowel Disease and Spondyloarthritis

Inclusion Criteria: * Confirmed diagnosis of Crohn's disease or Ulcerative Colitis disease based on confirmatory colonoscopy with biopsies, or if small bowel only, MRE with corresponding history * Age between 18 to 75 years old * Inflammatory bowel disease unclassified (IBD-U) subjects are eligible for inclusion if based on investigator assessment, the subject meets criteria for IBD-U, defined as chronic inflammatory bowel disease with overlapping features of Crohn's disease or ulcerative colitis * Initiating Guselkumab therapy in the next 30 days * Bio-naïve or bio-experienced\* to ≤3 mechanisms of action \*Defined as prior exposure or failure, as defined by inadequate efficacy or intolerance Exclusion Criteria: * Unable to provide consent for participation * Known SpA diagnosis, prior to screening * Has started Guselkumab therapy * Prior exposure to IL-23 therapy (like Mirikizumab, Ustekinumab, etc.) * Prior exposure to TB, active or currently undergoing treatment for latent TB * Pregnancy as some pregnancy symptoms could be mistaken for SpA symptoms * Prior exposure to combination advanced biologic therapies