The study will enroll approximately 213 patients. All participants will receive esomeprazole or esomeprazole placebo-matching capsules (this is a capsule that looks like esomeprazole but has no active ingredient) during a 7-week run-in period. Participants will then be randomly assigned (by chance, like flipping a coin) to one of the three treatment groups—which will remain undisclosed to the patient and study doctor during the study (unless there is an urgent medical need):