Abstract: Objective To investigate the important role of induced sputum in the diagnosis and treatment of chronic nonproductive cough by assessing its feasibility and the side effects which may occur during the procedure.Methods The diagnosis procedure was based on the anatomical protocol for diagnosing chronic nonproductive cough,42 patients who still could not be diagnosed would undertake induced sputum and bronchodilation or bronchial provocation test.Results Appropriate sputum samples were obtained by inducing sputum method in 41 of 42 patients with chronic nonproductive cough(41/42,97.6%).Side effects occurred in 4 patients(4/41,9.8%).The percentage of eosinophil counts in induced sputum was high in 25 of 41(25/41,61.0%),including cough variant asthma(CVA)(22/41,53.7%),eosinophilic bronchitis(EB)(3/41,7.3%);And the percentage of eosinophil counts in patients with induced sputum was not high in 16 of 41(16/41,39.0%),including post infectious cough(PIC)(4/41,9.8%),CVA(2/41,4.8%),gastroesophageal reflux(GER)(5/41,12.2%),indeterminate diagnosis(5/41,12.2%).After treatment,the percentage of eosinophil counts in patients with induced sputum was significantly reduced in CVA and EB.Conclusion Induced sputum procedure was an effective method for diagnosing chronic nonproductive cough and little side effects occurred during the procedure.Induced sputum can provide a reliable data of airway inflammation for the patients with chronic nonproductive cough in clinical diagnosis and treatment.

Key words: chronic nonproductive cough, induced sputum, diagnosis, treatment