User Groups Definition: Patients who used any dose of NSAIDs or aspirin via oral or systemic (intramuscular, Per rectal) route within 2 weeks prior to the onset of upper GI bleeding NSAID group: Clean base gastric or duodenal ulcer is required (i.e., patients with normal finding or erosions alone on endoscopy will not be eligible) Aspirin group: Either an ulcer or multiple (>5) erosions found on endoscopy