Study objectives: Eosinophilic bronchitis (EB) presents as a chronic cough and sputum eosinophilia without airflow limitation or bronchial hyperreactivity. Its long-term clinical course remains unknown. This study evaluated how frequently EB recurs and whether it develops chronic airway obstruction.
Design: This study was a prospective analysis.
Methods: Cough severity, FEV1, provocative concentration of methacholine causing a 20% fall in FEV1, and sputum eosinophil percentages were serially measured in 36 subjects for up to 48 months. All subjects inhaled corticosteroids until cough subsided.
Results: Five of the twenty four follow-up subjects (21%) had a recurrent episode of EB 4 to 6 months after disappearance of the first episode of EB (recurrent eosinophilic bronchitis). Progressive FEV1 reduction > 20% was observed in three of the subjects, including a subject with asthma developing at the ninth month. Nineteen subjects had no recurrence of cough (nonrecurrent eosinophilic bronchitis) and no progressive FEV1 reduction > 20%. However, sputum eosinophilia recurred between 4 months and 24 months in 10 subjects. Mean values of FEV1 at the ninth and 12th months of the study were significantly lower in the recurrent eosinophilic bronchitis group than in the nonrecurrent eosinophilic bronchitis group (p < 0.01).
Conclusion: These results suggest that repeated episode of EB is associated with the development of chronic airflow obstruction, including asthma.