Diagnostic accuracy of FeNO in asthma and predictive value for inhaled corticosteroid responsiveness: A prospective, multicentre study
Antonius Schneider, Benjamin Brunn, Alexander Hapfelmeier, Konrad Schultz, Christina Kellerer, Rudolf A. Jörres
Abstract
Background: Fractional exhaled nitric oxide (FeNO) is promising for diagnosing asthma and could replace bronchial provocation (BP). To date, cut-off values have been derived by post hoc analysis only. The aim was to validate the diagnostic accuracy for predefined FeNO cut-off values and the predictive value for responsiveness to inhaled corticosteroids (ICS). Methods: /VC) or airway resistance as assessed by whole body plethysmography, with additional BP or bronchodilation test. Follow-up was performed after 12 weeks. Analyses of Receiver Operating Characteristics curves were conducted to determine the diagnostic accuracy and predictive value of FeNO. Findings: < 0·001). Sensitivity at FeNO >50 ppb was 0·24 (95% CI 0·18-0·32), specificity 0·99 (0·95-1·0), positive predictive value (PPV) 0·95 (0·84-0·99), negative predictive value (NPV) 0·54 (0·48-0·60). In 66 patients with ´wheezing´ and ´allergic rhinitis´, the sensitivity at FeNO >33 ppb was 0·49 (0·34-0·64), specificity 0·88 (0·64-0·99), PPV 0·92 (0·75-0·99), NPV 0·38 (0·23-0·54). In 68 patients with ICS medication, responsiveness was predicted at the cut-off >43 ppb, with a sensitivity of 0·55 (95%CI 0·36-0·74), specificity 0·82 (0·66-0·92), PPV 0·70 (0·47-0·87), NPV 0·71 (0·56-0·84). Interpretation: FeNO measurement allows a valid ruling-in of an asthma diagnosis, whereas ruling-out of asthma is not possible. Enhanced probability of ICS responsiveness is also given with increased FeNO values. Funding: Circassia Germany gave 25% discount on the purchase of three NIOX VERO devices.