6. Is ≥85% compliant at taking their Run-in medication and completing their e-Diary. Compliance for taking the Run-in medication is defined as the medication provided (esomeprazole and placebo) taken for 85% of the 6 weeks Run-in Period (or on 36 of 42 days of the Run-in Period).Compliance for the e-Diary is defined as the percentage of scheduled assessments that are completed based on 2 assessments per day (daytime and nighttime). For randomization, 85% compliance is required and is defined as 12 of 14 assessments completed over the 7-day period (Day -21 to Day-14) prior to the single blind Placebo Run-in Period.