The predictive value of serum EOS% and FeNO in stable phase of COPD for the therapeutic effect of glucocorticoids

Objective To investigate the predictive value of peripheral blood eosinophil percentage (EOS%) and exhaled nitric oxide (FeNO) on the efficacy of inhaled corticosteroids (ICS) in patients with chronic obstructive pulmonary disease (COPD) at stable stage. Methods A total of 78 patients with stable COPD during the outpatient clinic from January 2017 to December 2018 were enrolled. EOS%, FeNO, and pulmonary function indicators [forced vital capacity(FVC), forced expiratory volume in 1 sec (FEV1), peak expiratory flow (PEF)] were measured after ICS-free elution. The questionnaire was used to assess the severity of the symptoms. The above indicators were reviewed after 4 weeks of ICS treatment. According to the improvement of pulmonary function and chronic obstructive pulmonary disease assessment (CAT) improvement , the patients were divided into effective and ineffective groups. Pearson correlation analysis and receiver operating characteristic (ROC) curve were used to analyze the predictive value of EOS% and FeNO for ICS. Results After ICS treatment, EOS% and FeNO were lower, FVC, FEV1, and PEF were higher than before, and CAT score was lower than before (P 0.05). The FeNO level in the effective group was higher than that in the ineffective group before and after ICS treatment, with statistically significant difference (P 0.05); the area under the ROC curve for EOS% prediction of ICS efficacy before treatment was 0.531 (P>0.05), with critical value 3.13%, the sensitivity 57.1% and specificity 52.4%, respectively. The area under the ROC curve of FeNO for ICS treatment before treatment was 0.628 (P<0.05), with critical value 30.00%, sensitivity and specificity (64.6% and 91.0%) respectively. Conclusions For patients with stable COPD, EOS% and FeNO levels are positively correlated with the improvement of FEV1 after ICS treatment. Both of them can predict the efficacy of ICS to a certain extent, and FeNO has higher predictive value than EOS%, which can be applied to clinical practice. Key words: Pulmonary disease, chronic obstructive; Eosinophils; Fractional exhaled nitric oxide; Inhaled glucocorticoid