title: Cigarette smoking and the risk of Barrett's esophagus: a systematic review and meta-analysis.
abstract: OBJECTIVE
  Barrett's esophagus (BE) is a premalignant condition to esophageal adenocarcinoma. It is currently not clear whether cigarette smoking increases the risk of developing BE, and no meta-analysis has been performed on the topic. We conducted a systematic review and meta-analysis, providing a quantitative estimate of the increased risk of BE associated with cigarette smoking, to help clarify whether a relationship exists between smoking and BE.
  
  
  METHODS
  Four electronic databases (Medline, PubMed, Embase, and Current Contents Connect) were searched to May 17, 2013, for observational studies of BE patients. We calculated pooled odds ratios (ORs) and 95% confidence intervals (CIs) using a random effects model for the association of smoking with BE. BE patients were compared with non-gastroesophageal reflux disease (GERD) controls as well as with population-based and GERD controls.
  
  
  RESULTS
  Thirty-nine studies comprising 7069 BE patients were included in the meta-analysis. Having ever-smoked was associated with an increased risk of BE compared with non-GERD controls (OR 1.44; 95% CI 1.20-1.74), population-based controls (OR 1.42; 95% CI 1.15-1.76), but not GERD controls (OR 1.18; 95% CI 0.75-1.86). The meta-analyses of the studies reporting the lowest and highest number of pack-years smoked showed an increased risk of BE (OR 1.41; 95% CI 1.22-1.63) and (OR 1.53; 95% CI 1.27-1.84), respectively.
  
  
  CONCLUSIONS
  Cigarette smoking was associated with an increased risk of BE. Being an ever-smoker was associated with an increased risk of BE in all control groups. A greater number of pack-years smoked was associated with a greater risk of BE.
authors.affiliation: The Whiteley-Martin Research Centre, The Discipline of Surgery, The University of Sydney, Sydney Medical School, Penrith, New South Wales, Australia.
authors.forename: Juliana
authors.initials: J
authors.lastname: Andrici
authors.forename: Michael R
authors.initials: MR
authors.lastname: Cox
authors.forename: Guy D
authors.initials: GD
authors.lastname: Eslick
mesh_terms: D001471:Barrett Esophagus / Q000209:etiology* / Q000517:prevention & control; D005260:Female; D006801:Humans; D016239:MEDLINE; D008297:Male; D039781:PubMed; D012306:Risk; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D013997:Time Factors
keywords: Barrett's esophagus; cigarettes; meta-analysis; smoking; tobacco