Effectiveness and Tolerance of IV vs SC Biological Drugs in Gastrointestinal Diseases

Inclusion Criteria: * Age ≥ 18 years; * Confirmed diagnosis of IBD (Crohn's disease, ulcerative colitis or indeterminate colitis) * Intravenous therapy with vedolizumab or infliximab; OR * Patients who for clinical reasons initiated subcutaneous vedolizumab or infliximab therapy at least 2 and up to 8 weeks after intravenous therapy with the same drugs for the prospective cohort and patients on subcutaneous vedolizumab and infliximab therapy for more than 8 weeks after intravenous therapy with the same drugs for the retrospective cohort; * Stable (at least 12 weeks) steroid-free IBD clinical remission, defined as a finding of Harvey Bradshaw Index3 (HBI) scores \< 5 or Partial Mayo Score 4.5 (PMS) \< 2 for patients with Crohn's disease or colitis ulcerative, respectively, assessed at the time of switching the drug to subcutaneous administration; * Ability to sign informed consent for participation in the study and to comply with the schedule of scheduled visits. Exclusion Criteria: * Patients with dietary or medication changes during the study period (for the prospective group) or who experienced dietary or medication changes in the 48 weeks between drug switching from intravenous to subcutaneous administration (for the retrospective group only) ; * Patients undergoing colectomy or with cutaneous ostomy; * Patients scheduled for hospitalization or surgery within the period of study participation; * Concomitant enrollment in other interventional experimental protocols; * Unstable personality or unable to adhere to protocol procedures; * Any clinical condition which, in the opinion of the investigators, may contraindicate enrollment in the study; * Refusal to sign informed consent to participate in the study.