Proton pump inhibitors and gastric cancer: a population-based cohort study

We read with great interest the recent article by Seo et al regarding the association of proton pump inhibitors (PPI) and gastric cancer.1 We want to congratulate the authors for their exemplary work as the prevalence of PPI in current clinical practice cannot be overstated. After reviewing the article, we have some comments to share with you. As mentioned in the Methods section and also in figure 1, the target cohort was defined as ‘new PPI users’ who were prescribed PPI for more than 30 consecutive days. Although we understood that the subjects underwent 365 days of continuous observation to be classified as new PPI users, we are curious to know if the remote history of PPI use (>365 days ago) was taken into consideration before enrolment into the target cohort. The authors have defined index date as the first day of a new …