Systematic review and meta-analysis: the relationship between the Helicobacter pylori dupA gene and clinical outcomes

BACKGROUND: In 2005, the first disease-specific Helicobacter pylori virulence factor that induced duodenal ulcer and had a suppressive action on gastric cancer has been identified, and was named duodenal ulcer promoting gene (dupA). However, the importance of the dupA gene on clinical outcomes is conflicting in subsequent studies. The aim of this study was to estimate the magnitude of the risk for clinical outcomes associated with dupA gene. METHODS: A meta-analysis of case-control studies which provided raw data on the infection rates with the dupA-positive H. pylori detected by polymerase chain reaction was performed. RESULTS: Seventeen studies with a total of 2,466 patients were identified in the search. Infection with the dupA-positive H. pylori increased the risk for duodenal ulcer by 1.41-fold (95% confidence interval [CI], 1.12-1.76) overall. Subgroup analysis showed that the summary odds ratio (OR) was 1.57 (95% CI, 1.19-2.06) in Asian countries and 1.09 (95% CI, 0.73-1.62) in Western countries. There was no association between the presence of the dupA gene and gastric cancer and gastric ulcer. Publication bias did not exist. CONCLUSION: Our meta-analysis confirmed the importance of the presence of the dupA gene for duodenal ulcer, especially in Asian countries.