Eosinophilic bronchitis is an important cause of chronic cough

Eosinophilic bronchitis presents with chronic cough and sputum eosinophilia , but without the abnormalities of airway function seen in asthma. It is im portant to know how commonly eosinophilic bronchitis causes cough, since in contrast to cough in patients without sputum eosinophilia, the cough respo nds to inhaled corticosteroids. We investigated patients referred over a 2- yr period with chronic cough, using a well-established protocol with the ad dition of induced sputum in selected cases. Eosinophilic bronchitis was dia gnosed if patients had no symptoms suggesting variable airflow obstruction, and had normal spirometric values, normal peak expiratory flow variability , no airway hyperresponsiveness (provocative concentration of methacholine producing a 20% decrease in FEV1 ([PC20] > 8 mg/ml), and sputum eosinophili a (> 3%). Ninety-one patients with chronic cough were identified among 856 referrals. The primary diagnosis was eosinophilic bronchitis in 12 patients , rhinitis in 20, asthma in 16, post-viral-infection status in 12 and gastr oesophageal reflux in seven. In a further 18 patients a diagnosis was estab lished. The cause of chronic cough remained unexplained in six patients. In all 12 patients with eosinophilic bronchitis, the cough improved after tre atment with inhaled budesonide 400 mu g twice daily, and in eight of these patients who had a follow-up sputum analysis, the eosinophil count decrease d significantly, from 16.8% to 1.6%. We conclude that eosinophilic bronchit is is a common cause of chronic cough, and that sputum induction is importa nt in the investigation of cough.