The cumulative proportions of patients with sustained symptomatic response (SSR), defined as free from acid regurgitation and heartburn for the last seven days, are recorded during the 8-week study period for each study group. All of the patients starting the treatment are included for the intention-to-treat (ITT) analysis of the rate of SSR. If patients have obvious symptoms despite continuous PPI usage and have an unscheduled visit to load up on additional PPIs during the study, the case is then dropped from the per-protocol (PP) analysis. In addition, patients lost to follow-up are excluded from the PP analysis to determine the rate of SSR. Besides comparing the difference of the rate of SSR between the two study groups, the study also determined whether patients with different CYP2C19 genotypes have differences in the cumulative rates of SSR after therapy between the two study groups.