title: Acoustic cough-reflux associations in chronic cough: potential triggers and mechanisms.
abstract: OBJECTIVE
  Central sensitization is thought to play a role in chronic cough and might explain the temporal association between cough and gastroesophageal reflux (GOR) in patients in whom non-GOR causes have been excluded. Using our novel simultaneous acoustic cough recording and impedance/pH monitoring technique, we aimed to explore this further by assessing such temporal associations and their relationship to the acidity, duration, and proximal extent of reflux and the presence of erosive disease and cough reflex sensitivity in unselected patients (ie, including non-GOR causes) with chronic cough.
  
  
  METHODS
  Twenty-four hour ambulatory acoustic cough monitoring with simultaneous impedance/pH recording was carried out in 71 unselected patients with chronic cough, aged 51-64 years (47 female). In addition, all patients underwent cough reflex sensitivity testing to citric acid, and 66 patients underwent gastroscopy. Temporal associations between cough and reflux were expressed using the symptom association probability.
  
  
  RESULTS
  Seventy percent of patients exhibited temporal associations, with 48% having a positive symptom association probability (SAP(R-C)) for cough preceded by reflux (mainly distal), 56% a positive symptom association probability (SAP(C-R (2 min))) for reflux preceded by cough, and 32% both. Moreover, SAP(R-C) positive patients had a more sensitive cough reflex (P = .03) but similar esophageal reflux exposure and erosive disease, together with similar prevalence of extraesophageal causes of cough compared with SAP(R-C) negative patients. Reflux immediately following cough was rare.
  
  
  CONCLUSIONS
  Cough temporally associates with reflux irrespective of proposed diagnoses, may be self-perpetuating in some patients, and is likely to be driven by central processes.
authors.affiliation: Respiratory Research Group, The University of Manchester, Manchester, UK. jacky.smith@manchester.ac.uk
authors.forename: Jaclyn A
authors.initials: JA
authors.lastname: Smith
authors.forename: Samantha
authors.initials: S
authors.lastname: Decalmer
authors.forename: Angela
authors.initials: A
authors.lastname: Kelsall
authors.forename: Kevin
authors.initials: K
authors.lastname: McGuinness
authors.forename: Helen
authors.initials: H
authors.lastname: Jones
authors.forename: Simon
authors.initials: S
authors.lastname: Galloway
authors.forename: Ashley
authors.initials: A
authors.lastname: Woodcock
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Houghton
mesh_terms: D000328:Adult; D000368:Aged; D002908:Chronic Disease; D019343:Citric Acid; D003371:Cough / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D017097:Electric Impedance; D050782:Esophageal pH Monitoring; D005260:Female; D005764:Gastroesophageal Reflux / Q000150:complications* / Q000175:diagnosis / Q000503:physiopathology; D005773:Gastroscopy; D006801:Humans; D008297:Male; D008875:Middle Aged; D018670:Monitoring, Ambulatory; D012018:Reflex; D012684:Sensory Thresholds; D013018:Sound Spectrography; D013997:Time Factors
chemical_list: D019343:Citric Acid