The relationship between sputum eosinophils and responses to treatment of inhaled glucocorticoids in patients with persistent asthma

Objective To evaluate the treatment responses of asthmatics with and without sputum eosinophilia to inhaled glucoeorticoids,and therefore to verify whether low sputum eosinophils predict poor response to treatment with inhaled glucocorticoids.Methods Forty-two symptomatic asthmatic patients, who had not received glucocorticoid therapy in the 3 months preceding the study,were examined before and 1 month and 3 months after treatment with inhaled glucoeorticoids.At each visit,all patients underwent spirometry,symptom scoring and sputum induction.The level of eosinophil cationic protein(ECP)in the sputum supernatants was measured by radioimmunoassay.The patients were divided into 2 groups according to sputum eosinophil(EOS)percentages,an EOS group(EOS3%)and a non-EOS group(EOS3%). The response to inhaled glucocorticoid therapy(as measured by symptom scores and FEV_1 % pred)and the changes of sputum measurements were compared between the 2 groups.Results In the EOS group,the baseline EOS[0.080(0.063-0.178)]and ECP level[(324±149)μg/L]were significantly higher than those of the non-EOS group[0.017(0.006-0.021)and(152±68)μg/L,respectively,t=4.40,3.33, both,all P0.01].Baseline FEV_1,FEV_1 % pred and symptom scores were not different between the 2 groups[EOS group:(1.98±0.67)L,(65±20)%,7.0(5.0-10.0),non-EOS group:(2.07±1.05) L,(66±27)%,5.0(2.0-9.0),t=-0.62,-0.09,1.32,respectively,all P0.05].After 1 month and 3 months inhaled glucocorticoid therapy,the sputum EOS,ECP,the symptom score,FEV_1 and FEV_1% pred were[0.019(0.010-0.060),[0.036(0.006-0.070);(173±153)μg/L,(173±122) μg/L;3.0(1.0-6.0),3.0(1.0-5.0);(2.42±0.64)L,(2.43±0.76)L;(77±13)%,(77± 18)%;respectively in the EOS group,which were significantly different as compared to baseline values (F=6.73,6.71,5.93,7.38,5.78,respectively,all P0.05).But in the non-EOS group,the sputum EOS,ECP,the symptom score,FEV_1 and FEV_1 % pred were 0.013(0.000-0.025),0.012(0.004- 0.031),(111±50)μg/L,(117±50)μg/L;3.0(0.0-6.0),3.0(1.0-7.3),(2.22±0.86)L, (2.21±0.24)L,(71±20)%,(65±21)%;respectively at 1 and 3 months,which showed that the sputum EOS,FEV_1 and FEV_1% pred did not change(F=1.98,0.80,1.37,respectively,all P0.05), but the ECP level and the symptom score improved(F = 3.78,3.59,respectively,both P0.05). Multiple stepwise regression showed that baseline FEV_1,severity degree and sputum EOS correlated significantly with changes in FEV_1 after treatment.Among the baseline indexes examined,sputum EOS had the highest negative predictive value(89.5%)for the response to treatment.Conclusions In asthmatics with low sputum EOS,inhaled glucocorticoid therapy for 3 months failed to improve pulmonary function.The result confirmed that low sputum EOS was the best predictor for poor glucocorticoid effect in asthma.