Clinical features of eosinophilic bronchitis

Joo, Jae hak; Park, Jin; Park, Sang Joon; Seo, Moon Jeong; Kim, Do Jin; Uh, Soo taek; Kim, Yong Hun; Park, Choon Sik

Abstract

BACKGROUND: Sputum examination is known to be a valid and reliable method in assessing airway inflammation. Eosinophilic inflammation of airway is usually associated with airway hyperresponsiveness and reversibility. But eosinophilic bronchitis present with chronic cough without the abnormality of airway function. The objectives of this study are 1) to investigate the incidence of eosinophilic bronchitis in the chronic cough syndrome and 2) to evaluate the clinical features of eosinophilic bronchitis.
METHODS
We evaluated 92 patients who had been coughing for more than 3 weeks. In addition to usual diagnostic protocol, we performed sputum analysis for differential cell count. Eosinophilic bronchitis was diagnosed if patients had normal spirometric values, normal peak expiratory flow variability, no airway hyperresponsiveness, and sputum eosinophilia (>3%).
RESULTS
The causes of chronic cough were post-nasal drip in 33%, cough variant asthma in 16%, bronchitis in 15%, and eosinphilic bronchitis in 12%. Initial eosinophil percentage in sputum of patients with eosinophilic bronchitis was 26.8+/-6.1% (3.8-63.7%). Treated with inhaled steroid, subjective improvement in cough and significant decrease in sputum eosinophil percentage (from 29.1 +/-8.3% to 7.4+/-3.3%) were observed. During the follow up period, increases in sputum eosinophil percentage with aggravation of symptom were found.
CONCLUSION
Eosinophilic bronchitis is an important cause of chronic cough. Assessment of airway inflammation by sputum examination is important in investigating the cause of chronic cough. Symptoms in eosinophilic bronchitis are effectively controlled by inhaled corticosteroid, but they may follow chronic course.