Exhaled nitric oxide in the diagnosis of asthma: comparison with bronchial provocation tests

Abstract

Background: Bronchial provocation tests such as exercise, methacholine (MCH), and adenosine-59-monophosphate (AMP) challenges are used extensively in the diagnosis of asthma. A study was undertaken to determine whether exhaled nitric oxide (eNO) can be used to diagnose asthma in patients with non-specific respiratory symptoms and to compare this test with conventional provocation tests. Methods: Patients with non-specific respiratory symptoms and normal spirometric parameters were included in the study. eNO was measured and exercise, MCH and AMP challenges performed in all subjects. Patients were defined as asthmatic based on clinical follow up 24 months after testing. Results: Forty patients were considered asthmatic and 45 were not. The area under receiver operating characteristic curves gave values of 0.896 for eNO, 0.781 for exercise, 0.924 for MCH, and 0.939 for AMP (p = 0.033, 0.575 and 0.085 for eNO v exercise, MCH and AMP respectively). From our data, a cut off value of NO .7 ppb at a flow rate of 250 ml/s best differentiates between asthmatics and nonasthmatics (sensitivity 82.5%, specificity 88.9%). Optimal cut off values for other tests were exercise: DFEV 1 >10% (sensitivity 57.9%, specificity 100%); PC 20 -MCH: (3 mg/ml (sensitivity 87.5%, specificity 86.7%); and PC 20 -AMP: (150 mg/ml (sensitivity 89.5%, specificity 95.6%). Conclusions: Measurement of eNO can be used as a safe, simple and rapid test for the diagnosis of asthma and is as good as bronchial provocation tests.

Features of severe asthma in school-age children: Atopy and increased exhaled nitric oxide

“…16,22 In subjects with mild asthma, F ENO correlates with the magnitude of airway eosinophilia 23 and bronchial hyper-responsiveness 24 and falls in a dose-dependent manner after the initiation of ICS. 25 Accordingly, F ENO in our study was lower in children with mild-to-moderate asthma treated with lower doses of ICS than in children with severe asthma on twice the amount of daily ICS.…”

Spirometry-Adjusted Fraction of Exhaled Nitric Oxide Allows Asthma Diagnosis in Children, Adolescents, and Young Adults

“…2 The predictive values for F ENO were shown to be sufficiently robust to be used in this area; they are more reliable than peak expiratory flow and spirometry 23 and similar to those associated with bronchial challenge tests. 2,[23][24][25] An increased F ENO value strengthens the basis for the diagnosis of asthma, principally because the airway inflammation in asthma is heterogeneous and is not always associated with increased F ENO (eg, neutrophillic airway inflammation); moreover, in subjects who have already been treated with inhaled steroids, the test may be falsely negative. 2 Thus, the importance of F ENO lies in its potential to identify steroid responsiveness rather than to make an apt clinical diagnosis.…”

The Clinical Utility of Fractional Exhaled Nitric Oxide (FeNO) in Asthma Management

“…24 studies with a total of 2,820 patients were included in KQ 1.c. The characteristics of these studies are in Appendix Tables C. [4][5][6]. The majority of the studies (15 studies) included only adults >18 years old; 8 studies had children with average age of 5-12 years and 1 included patients with average age of 13-18 years.…”

“…The detailed risk of bias assessment is presented in Appendix Tables G. 4 and G.5 and summarized in Figures 6 and 7 for RCTs and observational studies; respectively. The overall risk of bias was low in 36% of the RCTs and 50% of the observational studies.…”

“…Globally, asthma ranks 14 th based on the burden of disease, as measured by disability adjusted life years. 4 In US, asthma contributes significantly to health care resource utilization and associated costs. For example, in 2012, asthma was one of the top 20 leading diagnosis groups for primary care visits and was the main reason for 1.8 million emergency department visits and 439,000 hospitalizations.…”