title: Enteric Salmonella or Campylobacter infections and the risk of inflammatory bowel disease.
abstract: OBJECTIVE
  Enteric pathogens have been implicated in the aetiology of inflammatory bowel disease (IBD), but increased rates of stool testing of patients with unclear gastrointestinal symptoms might cause detection bias. Hence, the objective of this study was to analyse incidence rates of Crohn's disease and ulcerative colitis among patients with Salmonella- or Campylobacter-positive and negative stool tests and to study the incidence of positive and negative stool tests among patients already diagnosed with IBD.
  
  
  METHODS
  The Danish population was followed for 94.3 million person-years during 1992-2008 using national registers to identify persons with positive and negative stool tests and patients with IBD. Using Poisson regression, incidence rate ratios (IRRs) for IBD after positive or negative stool tests and, conversely, IRRs for positive and negative stool tests following IBD, were calculated.
  
  
  RESULTS
  IRRs for IBD were significantly high in the first year after Salmonella- or Campylobacter-positive stool tests (IRRs 5.4-9.8), and they remained moderately increased 1-10 years later (IRRs 1.6-2.2), and less so >10 years later (IRRs 0.8-1.8). However, IRRs for IBD <1 year after a negative stool test were several-fold higher (IRRs 53.2-57.5), and a decreasing incidence pattern over time was parallel to that following positive test results. Among patients with IBD, IRRs for subsequent positive and-most notably-negative stool test results were also significantly high.
  
  
  CONCLUSIONS
  Similarities in temporal risk patterns for IBD following positive or negative stool tests indicate that the increased occurrence of Salmonella- or Campylobacter-positive results around the time of first IBD hospitalisation results from detection bias.
authors.affiliation: Department of Epidemiology Research, Statens Serum Institut, Copenhagen S, Denmark.
authors.forename: Tine
authors.initials: T
authors.lastname: Jess
authors.forename: Jacob
authors.initials: J
authors.lastname: Simonsen
authors.forename: Nete Munk
authors.initials: NM
authors.lastname: Nielsen
authors.forename: Kristian Tore
authors.initials: KT
authors.lastname: Jørgensen
authors.forename: Peter
authors.initials: P
authors.lastname: Bager
authors.forename: Steen
authors.initials: S
authors.lastname: Ethelberg
authors.forename: Morten
authors.initials: M
authors.lastname: Frisch
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D002167:Campylobacter / Q000302:isolation & purification; D002169:Campylobacter Infections / Q000150:complications* / Q000453:epidemiology; D002648:Child; D002675:Child, Preschool; D003093:Colitis, Ulcerative / Q000453:epidemiology / Q000382:microbiology; D003424:Crohn Disease / Q000453:epidemiology / Q000382:microbiology; D003718:Denmark / Q000453:epidemiology; D004812:Epidemiologic Methods; D005243:Feces / Q000382:microbiology; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D015212:Inflammatory Bowel Diseases / Q000453:epidemiology / Q000382:microbiology*; D008297:Male; D008875:Middle Aged; D012475:Salmonella / Q000302:isolation & purification; D012480:Salmonella Infections / Q000150:complications* / Q000453:epidemiology; D055815:Young Adult