title: The association between Barrett's esophagus and Helicobacter pylori infection: a meta-analysis.
abstract: OBJECTIVE
  The effect of Helicobacter pylori on Barrett's esophagus is poorly understood. We conducted a meta-analysis to summarize the existing literature examining the effect that H. pylori has on Barrett's esophagus.
  
  
  METHODS
  We performed a comprehensive search to identify studies pertaining to the association between H. pylori and Barrett's esophagus. We conducted meta-regression analyses to identify sources of variation in the effect of H. pylori on Barrett's esophagus.
  
  
  RESULTS
  Our analysis included a total of 49 studies that examined the effect of H. pylori on Barrett's esophagus and seven studies that examined the effect of cag A positivity on Barrett's esophagus. Overall, H. pylori, and even more so cag A, tended to be protective for Barrett's esophagus in most studies; however, there was obvious heterogeneity across studies. The effect of H. pylori on Barrett's esophagus varied by geographic location and in the presence of selection and information biases. Only four studies were found without obvious selection and information bias, and these showed a protective effect of H. pylori on Barrett's esophagus (Relative risk = 0.46 [95% CI: 0.35, 0.60]).
  
  
  CONCLUSIONS
  Estimates for the effect of H. pylori on Barrett's esophagus were heterogeneous across studies. We identified selection and information bias as potential sources of this heterogeneity. Few studies without obvious selection and information bias have been conducted to examine the effect of H. pylori on Barrett's esophagus, but in these, H. pylori infection is associated with a reduced risk of Barrett's esophagus.
authors.affiliation: Department of Epidemiology, University of NorthTexas Health Science Center, 3500 Camp Bowie Boulevard Fort Worth, TX 76107, USA. lori.fischbach@unthsc.edu
authors.forename: Lori A
authors.initials: LA
authors.lastname: Fischbach
authors.forename: Helena
authors.initials: H
authors.lastname: Nordenstedt
authors.forename: Jennifer R
authors.initials: JR
authors.lastname: Kramer
authors.forename: Subi
authors.initials: S
authors.lastname: Gandhi
authors.forename: Sam
authors.initials: S
authors.lastname: Dick-Onuoha
authors.forename: Anthony
authors.initials: A
authors.lastname: Lewis
authors.forename: Hashem B
authors.initials: HB
authors.lastname: El-Serag
mesh_terms: D001471:Barrett Esophagus / Q000382:microbiology*; D004935:Esophageal Diseases / Q000382:microbiology*; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000302:isolation & purification / Q000502:physiology*; D006801:Humans