RESUMO
BACKGROUND: Fractional exhaled nitric oxide (FeNO) is an acceptable and noninvasive marker for defining eosinophilic airway inflammation. Further study is necessary to clarify the role of FeNO in patients with chronic obstructive pulmonary disease (COPD). This study aimed to determine the association between FeNO levels and clinical outcomes. METHODS: A prospective observational study was conducted at Songklanagarind Hospital from October 2020 to November 2022. FeNO testing and spirometry were performed at the initial visit and 12-month follow-up. Exacerbation, hospitalization, lung function decline, and all-cause mortality were analyzed to determine the association between FeNO levels and clinical outcomes. RESULTS: A total of 60 patients with COPD were enrolled, 88.3 % of whom were male, with a mean age of 71.3 ± 9.5 years. There were 18 patients (30 %) in the high FeNO group (≥25 ppb) and 42 patients (70 %) in the low (<25 ppb) FeNO group. The mean blood eosinophil count (BEC) was significantly higher in the high FeNO group (p < 0.001). After a 12-month follow-up period, high FeNO group had higher exacerbation events (HR of 1.26, 95 % confidence interval (CI), 1.10-1.97, p= 0.025). Hospitalization and mortality rates were significantly higher in the high FeNO group. Regardless of the inhaled corticosteroids used, patients with high BEC and FeNO levels tended to have a greater risk of exacerbation. CONCLUSION: In patients with COPD, FeNO levels are strongly correlated with BEC. Poor clinical outcomes were reported in patients with high FeNO levels. FeNO may be a useful biomarker for predicting clinical outcomes in patients with COPD.
RESUMO
Background: The blood eosinophil count (BEC) is an effective biomarker for predicting inhaled corticosteroid responsiveness in patients with chronic obstructive pulmonary disease (COPD). Methods: A 12-month prospective observational study was conducted in patients with COPD. BEC was measured at enrollment, and after 6 and 12 months. Patients were classified into 3 groups according to their baseline BEC: <100, 100-299, and ≥300 cells/µL. We aimed to describe the patterns of blood eosinophil stability in patients with stable COPD and compare the exacerbation rates and other clinical outcomes at 6 and 12 months. Results: A total of 252 patients with COPD were included. The <100, 100-299, and ≥ 300 cells/µL groups consisted of 14.7%, 38.9%, and 46.4% of patients, respectively. BEC stability was highest (85%) in the ≥300 cells/µL group for both durations. The lowest stability was observed in the <100 cells/µL group at 57% and 46% after 6 and 12 months, respectively. The persistent ≥300 cells/µL group had a higher incidence of moderate-to-severe exacerbation (incidence rate ratio [IRR] 2.44, 95% confidence interval [CI]: 1.13-5.27, p value 0.023), as well as severe exacerbation (IRR 2.19, 95%CI: 1.39-3.45, p value 0.001). Other patient-reported outcomes did not differ significantly between groups. Conclusion: Blood eosinophil levels had good stability in patients with COPD with a BEC ≥300 cells/µL and was associated with a high risk of exacerbation in the persistent ≥300 cells/µL group. The variability of BEC was higher in patients with COPD with a BEC <300 cells/µL.