This clinical study aims to be used to implement and validate the AIDA tool in two phases:
* Phase 1: Risk stratification and personalised recommendations \& Model development * Phase 2: Mechanistic Model (Bioresource) development \& testing
Subjects ≥ 18 years old with a diagnosis of GIM or previous or current H. pylori infection, to whom a gastroscopy is indicated within clinical care
Availability of a signed informed consent form to participate in the study
Patients to whom an endoscopy is performed for the follow-up of another illness such as oesophageal varices and/or for therapy such as endoscopic dilation, feeding tube placement or endoscopic resection
Subjects with a clinical diagnosis of gastric diseases other than GIM or GC
Patients who have received antimicrobials during the four weeks prior to the endoscopy
Patients who have received proton pump inhibitors and/or bismuth-based treatments at least two weeks prior to the endoscopy