Interactions among smoking, obesity, and symptoms of acid reflux in Barrett's esophagus.
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.
Smith
Kylie J
KJ
Queensland Institute of Medical Research, Post Office Royal Brisbane Hospital, Queensland 4029, Australia.
O'Brien
Suzanne M
SM
Smithers
B Mark
BM
Gotley
David C
DC
Webb
Penelope M
PM
Green
Adèle C
AC
Whiteman
David C
DC
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*