title: Gastro-oesophageal reflux, eosinophilic airway inflammation and chronic cough.
abstract: OBJECTIVE
  Patients with eosinophilic airway inflammation (EAI) often show a therapeutic response to corticosteroids. Non-invasive methods of diagnosing EAI are potentially useful in guiding therapy, particularly in conditions such as chronic cough, for which corticosteroids may not be the first-line treatment.
  
  
  METHODS
  The value of exhaled nitric oxide (ENO) in the diagnosis of EAI was prospectively investigated in a cohort of 116 patients with chronic cough of varying aetiology. An optimum cut-off value was derived for differentiating between EAI and non-EAI causes of chronic cough. As the diagnosis was gastro-oesophageal reflux in 70 patients (60.3% of the total), the possible relationship between ENO and EAI in the presence or absence of reflux was subsequently investigated.
  
  
  RESULTS
  The optimum value of ENO for differentiating EAI (32% of patients) from non-EAI causes of cough was 33 parts per billion (sensitivity 60.5%, specificity 84.6%). In the subgroup of patients with reflux, ENO was highly specific for the diagnosis of EAI (sensitivity 66%, specificity 100%). Conversely, in the patients without reflux, ENO did not discriminate between cough due to EAI or other causes (sensitivity 100%, specificity 28.9%).
  
  
  CONCLUSIONS
  These results suggest that the presence or absence of reflux should be taken into consideration when interpreting ENO measurements in the diagnosis of chronic cough associated with EAI.
authors.affiliation: Pneumology Service, Chronic Cough Unit, CIBER Epidemiología y Salud Pública (CIBERESP), Hospital Ramón y Cajal, Madrid, Spain. apacheco.hrc@salud.madrid.org
authors.forename: Adalberto
authors.initials: A
authors.lastname: Pacheco
authors.forename: Vicenta
authors.initials: V
authors.lastname: Faro
authors.forename: Ignacio
authors.initials: I
authors.lastname: Cobeta
authors.forename: Ana
authors.initials: A
authors.lastname: Royuela
authors.forename: Ian
authors.initials: I
authors.lastname: Molyneux
authors.forename: Alyn H
authors.initials: AH
authors.lastname: Morice
mesh_terms: D001249:Asthma / Q000175:diagnosis*; D001944:Breath Tests; D001991:Bronchitis / Q000175:diagnosis; D002908:Chronic Disease; D015331:Cohort Studies; D003371:Cough / Q000175:diagnosis*; D004802:Eosinophilia / Q000175:diagnosis*; D005260:Female; D005764:Gastroesophageal Reflux / Q000175:diagnosis*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009569:Nitric Oxide / Q000032:analysis; D011446:Prospective Studies; D012680:Sensitivity and Specificity
chemical_list: D009569:Nitric Oxide