Efficacy and Safety of TAK-438 for the Prevention of Recurrent Gastric or Duodenal Ulcers During Therapy of Low-dose Aspirin

Inclusion Criteria: 1. Participants who require continuous low-dose aspirin therapy during the treatment period with the study drug 2. Participants who have a history of ulcer in stomach or duodenum, endoscopically confirmed 3. Outpatient (including inpatient for examinations) Exclusion Criteria: 1. Participants scheduled to change the type and dosage regimen of low-dose aspirin 2. Participants with ulcers or bleeding in stomach or duodenum, endoscopically confirmed 3. Participants with small intestine bleeding, large intestine bleeding, or gastrointestinal bleeding of unknown etiology 4. Participants who have a history of surgery which affects gastric acid secretion (e.g., resection of upper gastrointestinal tract, vagotomy) or who are scheduled to undergo such surgery 5. Participants with a previous or current history of Zollinger-Ellison syndrome, or other gastric acid hypersecretion disorders 6. Participants with a previous or current history of aspirin-induced asthma