title: Helicobacter pylori infection as a cause of gastritis, duodenal ulcer, gastric cancer and nonulcer dyspepsia: a systematic overview.
abstract: OBJECTIVE
  To evaluate current evidence for a causal relation between Helicobacter pylori infection and gastritis, duodenal ulcer, gastric cancer and nonulcer dyspepsia.
  
  
  METHODS
  A MEDLINE search for articles published in English between January 1983 and December 1992 with the use of MeSH terms Helicobacter pylori, gastritis, duodenal ulcer, gastric cancer, dyspepsia and clinical trial; abstracts were excluded. Six journals and Current Contents were searched manually for pertinent articles published in that time frame.
  
  
  METHODS
  Original studies with at least 25 patients, case reports and reviews that examined the relation between H. pylori and the four gastrointestinal disorders; 350 articles were on gastritis, 122 on duodenal ulcer, 44 on gastric cancer and 96 on nonulcer dyspepsia.
  
  
  METHODS
  The quality of the studies was rated independently on a four-point scale. The strength of the evidence was assessed using a six-point scale for each of the eight established guidelines for determining a causal relation.
  
  
  RESULTS
  There was conclusive evidence of a causal relation between H. pylori infection and histologic gastritis. Koch's postulates for the identification of a microorganism as the causative agent of a disease were fulfilled for H. pylori as a causative agent of gastritis. There was strong evidence that H. pylori is the main cause of duodenal ulcers not induced by nonsteroidal anti-inflammatory drugs, but all of Koch's postulates were not fulfilled. There was moderate epidemiologic evidence of an association between chronic H. pylori infection and gastric cancer. There was a lack of convincing evidence of a causal association between H. pylori and nonulcer dyspepsia.
  
  
  CONCLUSIONS
  The evidence supports a strong causal relation between H. pylori infection and gastritis and duodenal ulcer and a moderate relation between such infection and gastric cancer. Further studies are needed to clarify the role of H. pylori in these disorders. Thus far, there is no evidence of a causal relation between H. pylori and nonulcer dyspepsia.
authors.affiliation: Division of Gastroenterology, Dalhousie University, Halifax, NS.
authors.forename: S J
authors.initials: SJ
authors.lastname: Veldhuyzen van Zanten
authors.forename: P M
authors.initials: PM
authors.lastname: Sherman
mesh_terms: D002908:Chronic Disease; D004381:Duodenal Ulcer / Q000382:microbiology*; D004415:Dyspepsia / Q000209:etiology*; D005756:Gastritis / Q000382:microbiology*; D016481:Helicobacter Infections / Q000150:complications*; D016480:Helicobacter pylori; D006801:Humans; D012008:Recurrence; D013274:Stomach Neoplasms / Q000209:etiology*