A study on the relevance of eosinophil counts in induced sputum and fractional concentration of exhaled NO and lung functions in asthmatics / 中华全科医师杂志

ABSTRACT

Objective To investigate the correlations between eosinophil counts in induced sputum and lung function (FENO) and evaluate these parameters in medication adjustment in patients with asthma.Methods Sixty-five outpatients with mild to moderate persistent asthma ( mild,32 ; moderate,33 ) from January to August 2008 were enrolled in the study.All were treated with combined medications comprising inhaled corticosteroids plus long-acting β2 agonists for 1 year.Lung function (FEV1％ and PEF％ ),eosinophil counts in induced sputum,FENO,and Asthma Control Test (ACT) scores were obtained at regular follow-up intervals.Twenty-one healthy volunteers served as controls,and lung function,eosinophil counts in induced sputum,and FENO were also obtained.Results Sixty-three subjects completed 1-year or longer follow-up.Lung function of 63 subjects recovered quickly in the early days and improved slowly during the following 6 months.FENO decreased from (61 ± 25 ) nmol/L at baseline to ( 32 ± 19 ) nmol/L by the third month (q =7.32,P＜0.05) and to (22 ± 12) nmol/L by the sixth month,which showed significant difference from normal controls [ ( 13 ± 8) nmol/L; q =6.63,P ＜ 0.05 ].Eosinophil counts in induced sputum of the asthma group at baseline were (0.093 ±0.023) × 109/L and decreased to (0.032 ±0.011)× 109/L by the third month,which was significantly different from baseline and normal controls [ (0.005 ±0.003) × 106/ml; q =5.49,P ＜0.05 and q =5.87,P ＜0.05,respectively].FENO showed a significantly positive correlation with eosinophil counts in induced sputum in the first 6 months (r1 =0.612,r2 =0.558,r3 =0.675; all P＜0.05) and a negative correlation with FEV1 (r1 =-0.537,r3 =-0.658,r6 ＝ -0.623,r9 =-0.537,r12 =-0.597 ; all P ＜0.05 ) at any time point of the study.The ACT score of 63 subjects at baseline was 14 ±3,and the scores after treatment for 1,3,6,9,and 12 months were 18 ±5,19 ±7,23 ±2,24 ± 1,and 24 ± 1,respectively; at the same time,significant difference was found ( F =5.72,P ＜ 0.05).Effectiveness was found according to the ACT score only 1 month after treatment.Conclusion The parameters of FENO and eosinophil counts in induced sputum were sensitive in the detection of airway inflammation and may be useful in evaluation of the efficacy of treatment and adjustment of medication regimens.