title: Is Helicobacter pylori infection associated with asthma risk? A meta-analysis based on 770 cases and 785 controls.
abstract: OBJECTIVE
  Helicobacter pylori (H. pylori) infection has been thought to play a critical role in disorders such as gastric and lung cancer. A number of studies have been devoted to the relationship between H. pylori infection and asthma risk, which have generated inconclusive results. In this study we aimed to derive a more precise estimation of the relationship.
  
  
  METHODS
  Meta-analyses evaluating the association of H. pylori infection and asthma risk were conducted and subgroup analyses on ethnicity and source of controls as well as CagA status were further conducted. Eligible studies were identified for the period up to Jul 2012.
  
  
  RESULTS
  A total of five case-control studies comprising 770 cases and 785 controls were lastly selected for analysis. The overall data failed to indicate a significant association of H. pylori infection and asthma risk (OR=1.01; 95%CI=0.82-1.24). Likewise, in the subgroup analysis regarding ethnicity, source of controls and CagA status, no associations could be observed.
  
  
  CONCLUSIONS
  The pooled data failed to suggest a marked association between H. pylori infection and asthma risk. Future studies are needed to confirm this conclusion.
authors.affiliation: Institute of Respiratory Diseases, Xinqiao Hospital, Third Military Medical University, Chongqing, China. wangyanflower@163.com
authors.forename: Yan
authors.initials: Y
authors.lastname: Wang
authors.forename: Yutian
authors.initials: Y
authors.lastname: Bi
authors.forename: Liang
authors.initials: L
authors.lastname: Zhang
authors.forename: Changzheng
authors.initials: C
authors.lastname: Wang
mesh_terms: D001249:Asthma / Q000150:complications*; D016022:Case-Control Studies; D016481:Helicobacter Infections / Q000150:complications* / Q000382:microbiology; D016480:Helicobacter pylori / Q000302:isolation & purification*; D006801:Humans