Objective: The association between proton pump inhibitor (PPI) use and gastric cancer related to Helicobacter pylori eradication has not been fully investigated in geographical regions with high risk of gastric cancer. We aimed to evaluate the association between PPIs and gastric cancer in Korea. Design: This study analysed the original and common data model versions of the Korean National Health Insurance Service database from 2002 to 2013. We compared the incidence rates of gastric cancer after 1-year drug exposure, between new users of PPIs and other drugs excluding PPIs, by Cox proportional hazards model. We also analysed the incidence of gastric cancer among PPI users after H. pylori eradication. Results: The analysis included 11 741 patients in matched PPI and non-PPI cohorts after large-scale propensity score matching. During a median follow-up of 4.3 years, PPI use was associated with a 2.37-fold increased incidence of gastric cancer (PPI≥30 days vs non-PPI; 118/51 813 person-years vs 40/49 729 person-years; HR 2.37, 95% CI 1.56 to 3.68, p=0.001). The incidence rates of gastric cancer showed an increasing trend parallel to the duration of PPI use. In H. pylori -eradicated subjects, the incidence of gastric cancer was significantly associated with PPI use over 180 days compared with the non-PPI group (PPI≥180 days vs non-PPI; 30/12 470 person-years vs 9/7814 person-years; HR 2.22, 95% CI 1.05 to 4.67, p=0.036). Conclusion: PPI use was associated with gastric cancer, regardless of H. pylori eradication status. Long-term PPIs should be used with caution in high-risk regions for gastric cancer.

Gastric cancer is the fifth most common cancer type worldwide and one of the most frequently diagnosed cancers in South Korea. In this study, we propose DeepPrevention, which comprises a prediction module to predict the possibility of progression from atrophic gastritis to gastric cancer and an explanation module to identify risk factors for progression from atrophic gastritis to gastric cancer, to identify patients with atrophic gastritis who are at high risk of gastric cancer. The data set used in this study was South Korea National Health Insurance Service (NHIS) medical checkup data for atrophic gastritis patients from 2002 to 2013. Our experimental results showed that the most influential predictors of gastric cancer development were sex, smoking duration, and current smoking status. In addition, we found that the average age of gastric cancer diagnosis in a group of high-risk patients was 57, and income, BMI, regular exercise, and the number of endoscopic screenings did not show any significant difference between groups. At the individual level, we identified that there were relatively strong associations between gastric cancer and smoking duration and smoking status.

Background/Aims: Conflicting results have been reported regarding the interaction between proton pump inhibitors (PPIs) and clopidogrel. We investigated whether concomitant PPI use influenced the risk of recurrence in patients with stroke and myocardial infarction (MI). Methods: This study used two databases for two different designs, the Korean National Health Insurance Service (NHIS) database for a self-controlled case series design, and the national sample cohort of the NHIS data base converted to the Observational Medical Outcomes Partnership-Common Data Model version for a cohort study based on large-scale propensity score matching. Results: In the PPI co-prescription group, recurrent hospitalization with stroke occurred in 17.6% of the 8201 patients with history of stroke, and recurrent MI occurred in 17.1% of the 1216 patients with history of MI within1 year. According to the self-controlled case series, the overall relative risk (RR) of recurrent stroke was 2.09 (95% confidence interval (CI); 1.83–2.38); the RR showed an increasing trend parallel to the time from the beginning of PPI co-prescription. In the cohort study, there was a higher incidence of recurrent stroke in the PPI co-prescription group (Hazard ratio (HR): 1.34, 95% CI: 1.01–1.76, p = 0.04). The overall RR of recurrent MI was 1.47 (95% CI; 1.02–2.11) in the self-controlled case series; however, there was no statistically significant difference in recurrent MI in the cohort study (HR:1.42, 95% CI:0.79–2.49, p = 0.23). The impact of individual PPIs on stroke and MI showed different patterns. Conclusions: A PPI co-prescription >4 weeks with clopidogrel was associated with hospitalization of recurrent stroke within 1 year of initial diagnosis; however, its association with recurrent MI remains inconclusive. The influence of individual PPIs should be clarified in the future.

Gastric cancer is a significant health concern in East Asia, where early risk prediction is critical for prevention. However, the scarcity of single-hospital electronic health records (EHRs) data limits the applicability and generalizability of machine learning models. To address this challenge, we propose an ensemble transfer learning framework for gastric cancer prediction using structured EHRs in a data-scarce single-hospital setting. Three base models, Support Vector Machine (SVM), Random Forest, and Deep Neural Network (DNN), were pretrained on a large-scale national dataset from the Republic of Korean National Health Insurance Service (NHIS) and fine-tuned on a smaller institutional dataset from Kangdong Sacred Heart Hospital (KSHH). These fine-tuned models were combined via stacking ensemble learning with logistic regression as a meta-learner. The proposed model achieved strong performance with precision 0.78, recall 0.92, F1-score 0.83, accuracy 0.91, and AUC 0.93. For interpretability, permutation feature importance and Shapley Additive Explanations (SHAP) were applied. Smoking status, gender, and hypertensive disorder were identified as key predictors consistent with previous studies. This study demonstrates the successful application of transfer learning to overcome data scarcity in single-hospital structured EHRs. Furthermore, our stacking ensemble strategy outperformed the individual fine-tuned models, offering a generalizable framework for gastric cancer prediction in data-scarce clinical settings.

Lim SH, et al. Ann Surg Treat Res. 2023 Oct;105(4):237-244. https://doi.org/10.4174/astr.2023.105.4.237

BACKGROUND: Proton pump inhibitors (PPIs) may potentially reduce clopidogrel’s antiplatelet effect and increase cardiovascular risk. The degree of CYP (cytochrome P450) 2C19 inhibition varies among PPIs. Few studies have evaluated individual PPIs by CYP2C19 inhibition strength across countries. This study aimed to compare the incidence of cardiovascular events between strong CYP2C19-inhibiting potency and weak CYP2C19-inhibiting potency (weak or non-CYP2C19–inhibiting PPIs) in patients receiving clopidogrel. METHODS: We conducted an international observational cohort study using 14 databases from the United States, South Korea, and Taiwan. We included patients aged ≥18 years who received clopidogrel with PPIs from 1985 to 2023. PPIs were classified into strong CYP2C19-inhibiting PPIs and weak or non-CYP2C19–inhibiting PPIs based on CYP2C19 inhibition. We compared the hazard ratios and 95% CIs for major adverse cardiovascular events, including myocardial infarction, stroke, and cardiovascular mortality, using the Cox proportional hazards model after 1:1 propensity score matching. Secondary outcomes included cardiovascular mortality, myocardial infarction, stroke, and all-cause mortality. A random-effects model calculated pooled hazard ratios and 95% CIs. Only databases meeting all diagnostic criteria were included in the meta-analysis. RESULTS: Large-scale propensity score matching identified 166 005 patient pairs. During the 365-day follow-up, the risk of major adverse cardiovascular events did not differ significantly between patients receiving clopidogrel plus strong CYP2C19-inhibiting PPIs and those receiving clopidogrel plus weak or non-CYP2C19–inhibiting PPIs (17.63 per 1000 person-years versus 16.82 per 1000 person-years; calibrated hazard ratio, 1.00 [95% CI, 0.79–1.26]). No significant difference was observed in the risk of secondary outcomes (calibrated hazard ratio, cardiovascular mortality 1.10 [95% CI, 0.87–1.39], myocardial infarction 0.98 [95% CI, 0.81–1.19], stroke 1.05 [95% CI, 0.87–1.27], and all-cause mortality 1.18 [95% CI, 0.93–1.50]). CONCLUSIONS: Concomitant use of clopidogrel and strong CYP2C19-inhibiting PPIs was not associated with a higher cardiovascular risk compared with concomitant use of clopidogrel and weak or non-CYP2C19–inhibiting PPIs. This large-scale study does not support the clinical significance of potential interactions between PPIs and clopidogrel.