Sputum cell counts and exhaled nitric oxide in patients with gastroesophageal reflux, and cough or asthma

Abstract

Background: Gastroesophageal reflux (GER) is commonly associated with chronic cough and asthma, but there is little or no information on the nature of any associated airway inflammation.

Objective: To observe whether the association with GER worsens airway inflammation in patients with chronic cough or asthma.

Patients and methods: The airway inflammatory indexes in induced sputum and exhaled air were examined in a cross-sectional study of 11 patients with cough and GER, nine patients with mildly symptomatic asthma and GER, nine patients with mildly symptomatic asthma without GER and nine normal, healthy control subjects. GER was shown objectively by 24 h ambulatory pH recording.

Results: The sputum total cell count, the proportion of neutrophils and macrophages, and the fibrinogen level were normal in all four groups, with no significant differences among the groups. The sputum eosinophil and metachromatic cell percentages, and eosinophil cationic protein levels were normal in patients with cough and GER. They were significantly increased in patients with asthma compared with healthy subjects (P<0.01) and patients with cough (P<0.01), but were not different between groups with and without GER. Exhaled nitric oxide levels showed similar results (P<0.01). The correlations between the number of episodes of reflux and the proportion of sputum eosinophils, neutrophils or exhaled nitric oxide were modest but not significant.

Conclusions: GER, when associated with cough or mildly symptomatic asthma, does not cause or aggravate existing airway inflammation as measured by induced sputum cell counts and fibrinogen level, or by exhaled nitric oxide.