Eosinophilic Bronchitis Is an Important Cause of Chronic Cough

Abstract

Eosinophilic bronchitis presents with chronic cough and sputum eosinophilia, but without the abnormalities of airway function seen in asthma. It is important to know how commonly eosinophilic bronchitis causes cough, since in contrast to cough in patients without sputum eosinophilia, the cough responds to inhaled corticosteroids. We investigated patients referred over a 2-yr period with chronic cough, using a well-established protocol with the addition of induced sputum in selected cases. Eosinophilic bronchitis was diagnosed 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 FEV(1) ([PC(20)] > 8 mg/ml), and sputum eosinophilia (> 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 gastroesophageal reflux in seven. In a further 18 patients a diagnosis was established. The cause of chronic cough remained unexplained in six patients. In all 12 patients with eosinophilic bronchitis, the cough improved after treatment with inhaled budesonide 400 micrograms twice daily, and in eight of these patients who had a follow-up sputum analysis, the eosinophil count decreased significantly, from 16.8% to 1.6%. We conclude that eosinophilic bronchitis is a common cause of chronic cough, and that sputum induction is important in the investigation of cough.

Airway inflammation, airway responsiveness and cough before and after inhaled budesonide in patients with eosinophilic bronchitis

“…Four subjects had previously been involved in a study investigating the prevalence of eosinophilic bronchitis, but the measurements in this study are independent of the previous report [3]. Subjects had a cough, no symptoms suggesting variable airflow obstruction, normal spirometric values, normal peak expiratory flow (PEF) variability (maximum within day amplitude percentage mean <20% over 2 weeks), a methacholine provocative concentration of histamine causing a 20% fall in forced expiratory volume in one second (FEV1; PC20) >16 mg .…”

“…Eosinophilic bronchitis is a recently recognized condition, which although a common cause of chronic cough [3,4], is not sufficiently prevalent to easily recruit for placebo controlled studies. Furthermore, the main focus of the current study was not the efficacy of treatment but the relative effects on upper and lower airway inflammation.…”

“…Typically patients with eosinophilic bronchitis have a cough productive of scanty sputum in the morning [3] in keeping with a bronchitic component to their cough. The current findings suggest that heightened cough sensitivity might also contribute.…”

“…The authors [3] and others [4] have shown that eosinophilic bronchitis is the cause of cough in 10±20% of patients presenting to a respiratory specialist. The reason for the different relationship between eosinophilic airway inflammation and disordered airway function in eosinophilic bronchitis compared with asthma is unknown.…”

“…The reason for the different relationship between eosinophilic airway inflammation and disordered airway function in eosinophilic bronchitis compared with asthma is unknown. Patients with eosinophilic bronchitis commonly have upper airway symptoms [2,3], so one possibility is that the inflammation is mainly localized to the upper airway. There is some evidence that the cough and sputum eosinophilia in patients with eosinophilic bronchitis improves with inhaled corticosteroids [2], arguing against predominant upper airway inflammation.…”