title: Interactions among smoking, obesity, and symptoms of acid reflux in Barrett's esophagus.
abstract: BACKGROUND
  Barrett's esophagus, a metaplastic precursor to esophageal adenocarcinoma, is becoming increasingly prevalent in many populations. Clinical studies suggest acid reflux causes Barrett's esophagus; however, no population-based estimates of risk have been reported, and the role of other health factors in modifying risk is unclear.
  
  
  METHODS
  We conducted a population-based case-control study in Brisbane, Australia. Cases were 167 patients with histologically confirmed Barrett's esophagus diagnosed between February and December 2003. Age-matched and sex-matched controls (n = 261) were randomly selected from a population register. Data on exposure to self-reported symptoms of acid reflux, smoking, obesity, and other factors were collected through self-completed questionnaires followed by telephone interview. Risks of Barrett's esophagus and Barrett's esophagus with dysplasia associated with these exposures were estimated by the odds ratio (OR) and 95% confidence interval (95% CI), both crude and adjusted for other factors.
  
  
  RESULTS
  Self-reported weekly episodes of acid reflux were associated with greatly increased risks of Barrett's esophagus (adjusted OR, 29.7; 95% CI, 12.2-72.6) and Barrett's esophagus with dysplasia (OR, 59.7; 95% CI, 18.5-193). Smoking was also associated with risk of Barrett's esophagus. We found evidence of interactions between symptoms of acid reflux and smoking and obesity. Obese people with self-reported symptoms of acid reflux had markedly higher risks of Barrett's esophagus (OR, 34.4; 95% CI, 6.3-188) than people with reflux alone (OR, 9.3; 95% CI, 1.4-62.2) or obesity alone (OR, 0.7; 95% CI, 0.2-2.4). Similarly, those reporting both acid reflux symptoms and smoking were at substantially higher risks of Barrett's esophagus (OR, 51.4; 95% CI, 14.1-188) than those reporting acid reflux or smoking alone.
  
  
  CONCLUSIONS
  Although history of symptoms of acid reflux is the principle factor associated with Barrett's esophagus, risks are substantially increased by obesity and smoking.
authors.affiliation: Queensland Institute of Medical Research, Post Office Royal Brisbane Hospital, Queensland 4029, Australia.
authors.forename: Kylie J
authors.initials: KJ
authors.lastname: Smith
authors.forename: Suzanne M
authors.initials: SM
authors.lastname: O'Brien
authors.forename: B Mark
authors.initials: BM
authors.lastname: Smithers
authors.forename: David C
authors.initials: DC
authors.lastname: Gotley
authors.forename: Penelope M
authors.initials: PM
authors.lastname: Webb
authors.forename: Adèle C
authors.initials: AC
authors.lastname: Green
authors.forename: David C
authors.initials: DC
authors.lastname: Whiteman
mesh_terms: D000368:Aged; D001471:Barrett Esophagus / Q000209:etiology*; D016022:Case-Control Studies; D005260:Female; D005764:Gastroesophageal Reflux / Q000150:complications*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000150:complications*; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*