Gastro-oesophageal reflux, eosinophilic airway inflammation and chronic cough

Respirology. 2011 Aug;16(6):994-9. doi: 10.1111/j.1440-1843.2011.02010.x.


Background and 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.

MeSH terms

  • Asthma / diagnosis*
  • Breath Tests
  • Bronchitis / diagnosis
  • Chronic Disease
  • Cohort Studies
  • Cough / diagnosis*
  • Eosinophilia / diagnosis*
  • Female
  • Gastroesophageal Reflux / diagnosis*
  • Humans
  • Male
  • Middle Aged
  • Nitric Oxide / analysis
  • Prospective Studies
  • Sensitivity and Specificity


  • Nitric Oxide