2.3 | Data extraction and quality assessment
Two researchers independently examined all potentially relevant papers, extracted the data, and assessed the quality of retrieved studies. Any disagreement was resolved by consensus. The extracted data were characteristics of the study population (adults or children), region, sample size, types of endoscopy devices, gold standard test for H. pylori infection, prevalence of H. pylori infection, and true and false positives and negatives. We used the Quality Assessment of Diagnostic Accuracy Studies 2 (QUADAS-2) checklist to evaluate the quality of the included studies(34).