title: Determinants of reflux-induced chronic cough.
abstract: Gastro-oesophageal reflux is considered to be an important contributing factor in chronic unexplained cough. It remains unclear why some reflux episodes in the same patient causes cough while others do not. To understand more about the mechanism by which reflux induces cough, we aimed to identify factors which are important in triggering cough.
  
  
  
  In this multicentre study, 49 patients with reflux-associated chronic cough were analysed using 24-hour pH-impedance-pressure monitoring. The characteristics of reflux episodes that were followed by cough were compared with reflux episodes not associated with cough.
  
  
  
  The majority (72.4%) of the reflux episodes were acidic (pH<4). Compared with reflux episodes that were not followed by cough, reflux episodes that were followed by a cough burst were associated with a higher proximal extent (p=0.0001), a higher volume clearance time (p=0.002) and a higher acid burden in the preceding 15 min window (p=0.019) and higher reflux burden in the preceding 30 min window (p=0.044). No significant difference was found between the two groups when looking at the nadir pH, the pH drop, the acid clearance time or the percentage of reflux episodes which were acidic.
  
  
  
  The presence of a larger volume of refluxate and oesophageal exposure to reflux for a longer period of time seems to play an important role in inducing cough, while the acidity of the refluxate seems to be less relevant. This helps explain the observation that most patients with chronic cough tend not to benefit from acid inhibitory treatment.
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Thomas V K
authors.initials: TVK
authors.lastname: Herregods
authors.affiliation: Translational Research Centre for Gastrointestinal Disorders, University Hospital Gasthuisberg, University of Leuven, Leuven, Belgium.
authors.forename: Ans
authors.initials: A
authors.lastname: Pauwels
authors.affiliation: Barts and the London School of Medicine, Queen Mary University of London, London, UK.
authors.forename: Jafar
authors.initials: J
authors.lastname: Jafari
authors.affiliation: Barts and the London School of Medicine, Queen Mary University of London, London, UK.
authors.forename: Daniel
authors.initials: D
authors.lastname: Sifrim
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: Albert J
authors.initials: AJ
authors.lastname: Bredenoord
authors.affiliation: Translational Research Centre for Gastrointestinal Disorders, University Hospital Gasthuisberg, University of Leuven, Leuven, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Tack
authors.affiliation: Department of Gastroenterology and Hepatology, Academic Medical Centre, Amsterdam, The Netherlands.
authors.forename: André J P M
authors.initials: AJPM
authors.lastname: Smout
mesh_terms: D000863:Antacids / Q000627:therapeutic use; D002908:Chronic Disease; D003371:Cough / Q000209:etiology* / Q000517:prevention & control; D017097:Electric Impedance; D005260:Female; D005764:Gastroesophageal Reflux / Q000150:complications* / Q000188:drug therapy; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008297:Male; D008365:Manometry; D008875:Middle Aged
chemical_list: D000863:Antacids
keywords: AMBULATORY pH MONITORING; GASTROESOPHAGEAL REFLUX DISEASE; OESOPHAGEAL REFLUX; PROTON PUMP INHIBITION