We read with interest the recent article by Niimi et al reporting low levels of exhaled breath condensate (EBC) pH in patients with chronic cough.1 We and others have described low EBC pH in association with airway inflammation in allergic asthma, cystic fibrosis, and chronic obstructive pulmonary disease.2–4 In these studies there is a relatively close association between inflammation and low pH which is shown by the further fall in pH during exacerbations.2 However, in non-asthmatic chronic cough, while there is a low grade inflammation present in some subjects, this is much less than would be required to invoke inflammation as the major cause of airway acidification. It is unclear from the description of the …

Gastroesophageal reflux (GOR) disease is one of the 3 commonest causes of chronic cough. It can be difficult to diagnose as the traditionally recognised symptoms of GOR, such as heartburn and acid regurgitation, are often absent. More subtle indicators of a link between the cough and the oesophagus should therefore be sought. These include cough which occurs in relation to eating or phonation, cough which settles at night and does not tend to wake the patient from sleep and symptoms suggestive of laryngopharyngeal reflux. Investigations such as oesophageal manometry and 24 hour pH monitoring can be useful in characterising any underlying oesophageal abnormality, but may underestimate the problem since non-acid reflux can precipitate cough. Empirical trials of treatment are therefore often employed, but should be continued for at least 2 months, as symptoms can be slow to improve due to plasticity of the cough reflex. Pharmacologic treatment options include proton pump inhibitors, H2 receptor antagonists, pro-motility agents and liquid alginate preparations. Surgical fundoplication can also be effective when performed in appropriately selected individuals.