title: Irritable bowel, smoking and oesophageal acid exposure: an insight into the nature of symptoms of gastro-oesophageal reflux.
abstract: BACKGROUND
  In gastro-oesophageal reflux disease, oesophageal acid exposure correlates with symptoms but explains only a small fraction of their variance.
  
  
  OBJECTIVE
  To elucidate the effects of irritable bowel syndrome and smoking on gastro-oesophageal reflux disease symptoms and to clarify whether they modulate the relationship between oesophageal acid exposure and symptoms.
  
  
  METHODS
  The relationship between oesophageal acid exposure, irritable bowel syndrome (Rome I criteria), smoking status and symptoms was investigated in patients with a normal gastroscopy who underwent a 24-h oesophageal pH monitoring.
  
  
  RESULTS
  Of 256 patients with gastro-oesophageal reflux disease, 16% were smokers and 50% met the criteria for irritable bowel syndrome (irritable bowel syndrome+). The extent of oesophageal acid exposure was unrelated to smoking or irritable bowel syndrome status. Oesophageal acid exposure, irritable bowel syndrome status and current smoking independently predicted symptoms. Irritable bowel syndrome and smoking modulated the effect of oesophageal acid exposure on symptoms: oesophageal acid exposure was predictive of symptoms only in non-smokers. However, irritable bowel syndrome was a significant predictor of symptoms both in smokers and in non-smokers. Smoking was associated with symptoms only in irritable bowel syndrome+, while oesophageal acid exposure was associated with symptoms irrespective of irritable bowel syndrome status.
  
  
  CONCLUSIONS
  In patients with non-erosive gastro-oesophageal reflux disease, smoking and irritable bowel syndrome independently predicted symptoms, without affecting the extent of oesophageal acid exposure. The relationship between oesophageal acid exposure and symptoms was affected significantly, and in opposite directions, by smoking and irritable bowel syndrome.
authors.affiliation: Gastroenterology Unit, Hadassah-Hebrew University Medical Centre, Jerusalem, Israel. zimmerj@yahoo.com
authors.forename: J
authors.initials: J
authors.lastname: Zimmerman
mesh_terms: D000328:Adult; D005260:Female; D005744:Gastric Acid / Q000502:physiology*; D005764:Gastroesophageal Reflux / Q000209:etiology*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D043183:Irritable Bowel Syndrome / Q000150:complications*; D008297:Male; D008875:Middle Aged; D012737:Sex Factors; D012907:Smoking / Q000009:adverse effects*