Relationship between bronchial asthma severity and ensinophil percentage of induced sputum

Objective The eosinophil percentage of induced sputum was observed in persistent asthmatics with different severity,stable stages,and assessed its relationship with lung function.Methods The 63 patients with persistent asthma were recruited from clinic.The range of disease severity was classified into mild,moderate and severe persistent according to Global Initiative for Asthma.Sputum was induced by hypertonic saline aerosol inhalation,and lung function was performed in all patients.All of the data were had analyses by SPSS 15.0.Data among groups were compared by Kruskal-Wallis test,Mann-Whitney U test was used for the comparison between two groups.The correlation between eosinophil counting and lung function was assessed by Spearman rank-order method.Results ① There were progressively increasing percentage of eosinophils in sputum which related to asthma severity in persistent steroid-naive asthmatic patients.The percentage of eosinophils in sputum from severe asthmatics were significantly higher than mild asthmatics(41.8% vs 17.8%,P=0.033).However,there was no significant difference between mild and moderate,nor moderate and severe asmatics.②In the mild,moderate and severe asthmatics group,percentage of eosinophils in sputum was neither correlated with FEV1(r=-0.111,P>0.05),nor correlated with FEV1/FVC(r=-0.154,P>0.05).Conclusions There was higher percentage of eosinophils in sputum in servere persist asthmatics.However,disease severity could not reflect the airway inflammation accurately. Key words: Asthma; Airway inflammation; Induced sputum; Eosinophil; lung function