Effect of inhaled corticosteroids on symptom severity and sputum mediator levels in chronic persistent cough

Abstract

Background Chronic cough often lasts for more than 1 year and is associated with airway inflammation. The effect of inhaled corticosteroids on symptom severity and inflammatory mediator levels in these patients is unknown. Objective We sought to determine whether inhaled corticosteroids reduce cough severity and sputum mediator concentrations in patients with chronic persistent cough. Methods We performed a double-blind, randomized, placebo-controlled crossover study with inhaled fluticasone, 500 μg twice daily, and placebo for 14 days in 88 patients with cough for more than 1 year, with normal chest radiography and spirometry results. Outcome measures were a daily cough visual analogue scale and induced sputum concentrations of eosinophilic cationic protein (ECP), myeloperoxidase, leukotriene B4 (LTB4), leukotrienes C4/D4/E4 (cysteinyl leukotrienes [Cys-LTs]), prostaglandin E2 (PGE2), IL-8, and TNF-α. Sputum cell counts, exhaled nitric oxide levels, and carbon monoxide levels were also measured. Results There was a significant improvement in the cough visual analogue scale after inhaled fluticasone compared with placebo (mean difference, 1.0; 95% CI, 0.4-1.5; P < .001). LTB4, Cys-LT, and PGE2 levels were increased in all causes of cough. Sputum ECP counts, exhaled nitric oxide levels, and carbon monoxide levels decreased significantly after inhaled fluticasone. There was no change in sputum cell counts and other mediator concentrations. Conclusion Cough severity and sputum ECP levels are modestly reduced by inhaled corticosteroids in patients with chronic cough persisting for more than 1 year. LTB4, Cys-LT, PGE 2, IL-8, myeloperoxidase, and TNF-α levels are unaltered by this therapy. This raises the possibility that drugs targeted to reduce the effects of these mediators might be of benefit in chronic persistent cough.