RESUMO
Objective: To explore the diagnostic value of fractionated exhaled nitric oxide (FeNO) measurement in patients with asthma-chronic obstructive pulmonary disease(COPD) overlap syndrome (ACOS). Methods: Eighty-one patients with ACOS, 76 patients with asthma, 82 patients with COPD and 39 healthy non-smoking subjects were recruited in the study. Naku Lun breath analyzer was used to measure the level of FeNO in the 4 groups. Pulmonary function was also measured. The ROC curve was used to differentiate ACOS from patients with COPD. The correlation between FeNO and lung function was analyzed with Pearson correlation analysis. Results: The levels of FeNO in asthmatic group, COPD group, ACOS group and healthy group were (102.3±8.2)×10(9,) (23.7±0.6)×10(9,) (50.2±3.2)×10(9,) and (18.5±7.1)×10(9) respectively. Among the former 3 groups, the differences of FeNO were statistically significant (P<0.05). FeNO>29×10(9) was the best cutoff point to differentiate ACOS from COPD; the sensitivity was 80%, specificity was 73%, positive predictive value was 75%, and negative predictive value and accuracy was 79% and 77%. There was no correlation between FeNO and FEV(1)% or FEV(1)/FVC in ACOS, COPD and asthma groups (r=0.12, 0.11, P>0.05; r=0.11, 0.03, P>0.05; r=0.06, 0.08, P>0.05). Conclusion: FeNO is a good marker to help clinicians differentiate ACOS from COPD. FeNO>29×10(9) was the best cutoff point for the identification of patients with ACOS from COPD.
