Relationship between exhaled nitric oxide and treatment response in COPD patients with exacerbations

Background and objective: Fractional exhaled nitric oxide (FENO) has been implicated as a pulmonary biomarker in various respiratory diseases, including COPD. In this longitudinal study, the benefit of measuring FENO in a routine clinical setting was assessed in COPD patients hospitalized with an exacerbation of the disease. Methods: FENO, lung function and blood gases were measured in 58 COPD patients at hospital admission due to an exacerbation, and at discharge following treatment with corticosteroids and bronchodilators. Results: FENO levels were significantly decreased at discharge, compared with those at admission (geometric mean 25.3 ppb (95% CI: 21.2–30.1) vs 19.7 ppb (95% CI: 17.2–22.6); P = 0.002). There was a significant positive correlation between FENO concentrations at admission and the increase in FEV₁ after treatment (r = 0.441, P < 0.001), and a significant inverse correlation between FENO values at admission and the mean length of hospital stay (r = ?0.297, P = 0.016). Using receiver operating characteristic curve analysis, the optimum cut point for FENO as a predictor for significant increase in FEV₁ was 26.8 ppb (sensitivity: 74%, specificity: 75%). There were no correlations between FENO levels and absolute values for lung function variables at admission or discharge. Conclusions: These data suggest that FENO levels determined at hospital admission may predict the overall response to treatment in COPD patients with acute exacerbations.