The presence of other inflammatory cells and mediators in the airways of subjects with nonasthmatic chronic cough may be important in its pathogenesis. In a recent study of 19 subjects with chronic cough of varying etiology, induced sputum showed a predominance of neutrophils and increased levels of tumour necrosis factor-alpha and interleukin (IL)-8. Other proinflammatory mediators that are localized to sensory nerves in the airways, such as substance P, may also be involved in the pathogenesis but have not been investigated.
In the present study, we selected patients with a chronic cough who did not have asthma or an other known cause for the cough. We examined the characteristics of the airway inflammation by using induced sputum and the effects of treatment with inhaled budesonide in a randomized controlled trial. The study was designed to compare the treatment effect in patients with the eosinophilic versus noneosinophilic sputum but, by chance, no patient presented with eosinophilia. We also documented the local side effects of budesonide because its use in the treatment of chronic cough is not an approved use of the drug.