International Journal of COPD (Aug 2020)

Predictive Value of Exhaled Nitric Oxide and Blood Eosinophil Count in the Assessment of Airway Eosinophilia in COPD

  • Antus B,
  • Paska C,
  • Barta I

Journal volume & issue
Vol. Volume 15
pp. 2025 – 2035

Abstract

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Balazs Antus,1,2 Csilla Paska,1 Imre Barta1 1Department of Pathophysiology, National Koranyi Institute of Pulmonology, Budapest H-1121, Hungary; 2Department of Pulmonology, National Koranyi Institute of Pulmonology, Budapest H-1121, HungaryCorrespondence: Balazs AntusDepartment of Pathophysiology, National Koranyi Institute of Pulmonology, Piheno ut 1, Budapest H-1121, HungaryTel +36 1 391 3309Fax + 36 1 200 7060Email [email protected]: Fractional exhaled nitric oxide (FENO50) level and peripheral blood eosinophil count may serve as indicators of airway eosinophilia. The aim of this study was to estimate the diagnostic value of these markers for detecting airway eosinophilia in patients with stable chronic obstructive pulmonary disease (COPD) and those experiencing an acute exacerbation (AECOPD).Patients and Methods: FENO50 levels, sputum and blood eosinophil counts were assessed in 53 clinically stable ex-smoker COPD patients and 67 ex-smoker COPD patients experiencing a severe exacerbation. In AECOPD, clinical variables were measured at the time of hospital admission and discharge following treatment.Results: In stable COPD, blood eosinophil count but not FENO50 level was found to be a good predictor of airway eosinophilia (area under the receiver operating characteristic curve [ROC AUC]: ≥ 0.82). The sensitivity and the specificity of the test ranged between 75% and 98%, the negative predictive value (NPV) was high (> 90%). In AECOPD, FENO50 was predictive for airway eosinophilia (ROC AUC: > 0.8) with high NPV (> 88%), but with lower sensitivity and specificity (64– 70%). In contrast, the predictive accuracy of blood eosinophil count for airway eosinophilia in AECOPD was modest (ROC AUC: 0.54– 0.63). The combined use of the two markers provided only limited additional benefit. Correlation analyses supported ROC curve findings.Conclusion: In stable COPD the peripheral blood eosinophil count, while in AECOPD the FENO50 level is a good surrogate marker of airway eosinophilia.Keywords: biomarker, exacerbation, predictive, sensitivity, specificity, surrogate

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