title: Diagnosis of Helicobacter Pylori Infection is Associated with Lower Prevalence and Subsequent Incidence of Crohn's Disease.
abstract: OBJECTIVE
  Helicobacter pylori infection may protect against some chronic inflammatory diseases. This study examined H. pylori infection and its association with the prevalence of the gastrointestinal diseases Crohn's disease [CD], ulcerative colitis [UC], and coeliac disease [CeD]. Incident cases in a follow-up period after H. pylori testing were recorded to investigate if protective effects of H. pylori persisted after probable eradication.
  
  
  METHODS
  This was a historical cohort study performed in the Central Denmark Region. Patients were enrolled consecutively from primary health care centres after a urea breath test [UBT] for H. pylori and were then followed for a median of 6 years. The patient's diseases, country of birth, and gender were acquired from nationwide administrative registries. We used logistic regression to compare the prevalences of CD, UC, and CeD and Cox regression to compare the incidences of CD, UC, and CeD between H. pylori-positive and H. pylori-negative patients, adjusting for confounding variables.
  
  
  RESULTS
  We found a lower prevalence of CD in H. pylori-positive than in H. pylori-negative patients (odds ratio = 0.36 [0.17-0.75]). There were fewer incident cases of CD in H. pylori-positive than H. pylori-negative patients in the follow-up period (hazard ratio = 0.59 [0.36-0.96]). Similar trends were found for CeD but not for UC.
  
  
  CONCLUSIONS
  H. pylori infection may be a protective factor against the development of CD. However, the incidence of CD is still reduced after UBT and probable H. pylori eradication; thus, H. pylori status may be a marker for other factors that protect against CD.
authors.affiliation: Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark larsbart@rm.dk.
authors.forename: Lars E
authors.initials: LE
authors.lastname: Bartels
authors.affiliation: Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark Department of Clinical Epidemiology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Jepsen
authors.affiliation: Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Lisbet A
authors.initials: LA
authors.lastname: Christensen
authors.affiliation: Institute of Regional Health Research, University of Southern Denmark, Odense, Denmark.
authors.forename: Lars U
authors.initials: LU
authors.lastname: Gerdes
authors.affiliation: Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Hendrik
authors.initials: H
authors.lastname: Vilstrup
authors.affiliation: Department of Hepatology and Gastroenterology, Aarhus University Hospital, Aarhus, Denmark.
authors.forename: Jens F
authors.initials: JF
authors.lastname: Dahlerup
mesh_terms: D000328:Adult; D002446:Celiac Disease / Q000453:epidemiology; D003093:Colitis, Ulcerative / Q000453:epidemiology; D003424:Crohn Disease / Q000453:epidemiology*; D003430:Cross-Sectional Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000453:epidemiology; D016480:Helicobacter pylori; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors
keywords: Crohn’s disease; Helicobacter pylori; colitis ulcerative