title: Antibiotics associated with increased risk of new-onset Crohn's disease but not ulcerative colitis: a meta-analysis.
abstract: OBJECTIVE
  The objective of this study was to perform a meta-analysis investigating antibiotic exposure as a risk factor for developing inflammatory bowel disease (IBD).
  
  
  METHODS
  A literature search using Medline, Embase, and Cochrane databases was performed to identify studies providing data on the association between antibiotic use and newly diagnosed IBD. Included studies reported Crohn's disease (CD), ulcerative colitis (UC), or a composite of both (IBD) as the primary outcome and evaluated antibiotic exposure before being diagnosed with IBD. A random-effects meta-analysis was conducted to determine overall pooled estimates and 95% confidence intervals (CIs).
  
  
  RESULTS
  A total of 11 observational studies (8 case-control and 3 cohort) including 7,208 patients diagnosed with IBD were analyzed. The pooled odds ratio (OR) for IBD among patients exposed to any antibiotic was 1.57 (95% CI 1.27-1.94). Antibiotic exposure was significantly associated with CD (OR 1.74, 95% CI 1.35-2.23) but was not significant for UC (OR 1.08, 95% CI 0.91-1.27). Exposure to antibiotics most markedly increased the risk of CD in children (OR 2.75, 95% CI 1.72-4.38). All antibiotics were associated with IBD, with the exception of penicillin. Exposure to metronidazole (OR 5.01, 95% CI 1.65-15.25) or fluoroquinolones (OR 1.79, 95% CI 1.03-3.12) was most strongly associated with new-onset IBD.
  
  
  CONCLUSIONS
  Exposure to antibiotics appears to increase the odds of being newly diagnosed with CD but not UC. This risk is most marked in children diagnosed with CD.
authors.affiliation: Division of Gastroenterology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Ryan
authors.initials: R
authors.lastname: Ungaro
authors.affiliation: University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Charles N
authors.initials: CN
authors.lastname: Bernstein
authors.affiliation: University of Otago, Christchurch, New Zealand.
authors.forename: Richard
authors.initials: R
authors.lastname: Gearry
authors.affiliation: Statens Serum Institut, Copenhagen, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Hviid
authors.affiliation: Children's Hospital, University of Helsinki, Helsinki, Finland.
authors.forename: Kaija-Leena
authors.initials: KL
authors.lastname: Kolho
authors.affiliation: Seattle Children's Hospital, Seattle, Washington, USA.
authors.forename: Matthew P
authors.initials: MP
authors.lastname: Kronman
authors.affiliation: University of Manitoba, Winnipeg, Manitoba, Canada.
authors.forename: Souradet
authors.initials: S
authors.lastname: Shaw
authors.affiliation: University of Connecticut, Storrs, Connecticut, USA.
authors.forename: Herbert
authors.initials: H
authors.lastname: Van Kruiningen
authors.affiliation: Division of Gastroenterology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Jean-Frédéric
authors.initials: JF
authors.lastname: Colombel
authors.affiliation: Division of Gastroenterology, Icahn School of Medicine at Mount Sinai, New York, New York, USA.
authors.forename: Ashish
authors.initials: A
authors.lastname: Atreja
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D003093:Colitis, Ulcerative / Q000139:chemically induced; D003424:Crohn Disease / Q000139:chemically induced*; D006801:Humans; D012307:Risk Factors
chemical_list: D000900:Anti-Bacterial Agents