Relationship of eosinophils in induced sputum with bronchial responsiveness to methacholine or capsaicin and with responses to anti-asthmatic treatment in chronic cough patients / 천식및알레르기

ABSTRACT

BACKGROUND: The value of the induced sputum examination in chronic cough has not been determined. We performed this study to investigate the relationship between eosinophil percentage on induced sputum and bronchial responsiveness to methacholine or capsaicin, and responses to anti-asthmatic treatment in chronic cough patients. SUBJECTS AND METHODS: Forty-seven patients with chronic cough persisting for more than 1 month without current wheezing or dyspnea were studied. According to the eosinophil percentage on induced sputum, the subjects were divided into two groups group A (sputum eosinophil > or = 3%) and group B (sputum eosinophil < 3%). Methacholine bronchial provocation test (MBPT) and capsaicin challenge, and responses to anti-asthmatic treatment were compared between the two groups. RESULTS: Group A consisted of 26 subjects and group B consisted of 21 subjects. There were no differences in sex, clinical characteristics of cough, atopy prevalence, and peripheral eosinophil counts except serum IgE level between the two groups. MBPT positivity was much higher in group A than group B (46.2% vs 0%, p<0.001), but there was no difference in capsaicin test positivity (44.0% vs 50.0%). Group A showed much higher response rates to anti-asthmatic treatments than in group B (73.1% vs 19.0%, p<0.001). CONCLUSION: Eosinophilic airway inflammation in chronic cough was related to methacholine bronchial hyperresponsiveness, but not to capsaicin cough threshold. Induced sputum eosinophil percentage was a good indicator in predicting the response to anti-asthmatic treatment in most chronic cough patients.