Exhaled nitric oxide in the diagnosis of asthma in adults: a systematic review

Abstract

Summary Objectives To identify and synthesize evidence on the diagnostic accuracy of FENO for asthma in adults. Materials and Methods Systematic searches (nine key biomedical databases and trial registers) were carried out on November 2014. Records were included if they recruited patients with the symptoms of asthma; used a single set of inclusion criteria; measured FENO50 in accordance with American Thoracic Society guidelines, 2005 (off‐line excluded); reported/allowed calculation of true‐positive, true‐negative, false‐positive and false‐negative patients as classified against any reference standard. Study quality was assessed using QUADAS II. Meta‐analysis was planned where clinical study heterogeneity allowed. Rule‐in and rule‐out uses of FENO were considered. Results A total of 4861 records were identified originally and 1312 in an update. Twenty‐seven studies were included. Heterogeneity precluded meta‐analysis. Results varied even within subgroups of studies. Cut‐off values for the best sum of sensitivity and specificity varied from 12 to 55 p.p.b., but did not produce high accuracy. 100% sensitivity or 100% specificity was reported by some studies indicating potential use as a rule‐in or rule‐out strategy. Conclusions and Clinical Relevance FENO50 had variable diagnostic accuracy even within subgroups of studies with similar characteristics. Diagnostic accuracy, optimal cut‐off values and best position for FENO50 within a pathway remain poorly evidenced.

Priorities for future research into asthma diagnostic tools: A PAN‐EU consensus exercise from the European asthma research innovation partnership (EARIP)

“…10 Therefore, elevated FeNO is assumed to reflect an eosinophilic asthma phenotype, which account for approximately 50% of all asthmatics seen in clinical practice although higher in children. 16,17 Asthma monitoring FeNO has been proposed as a biomarker that may help the clinician to manage asthma. 10 Combining FeNO and peripheral eosinophil counts seems to be a better approach than just using FeNO values.…”

“…15 However, it should be always be kept in mind that asthma cannot be ruled out when symptoms are compatible with the condition despite low values of FeNO, as asthma is not necessarily eosinophilic. 16,17 Asthma monitoring FeNO has been proposed as a biomarker that may help the clinician to manage asthma. 18,19 FeNO values above 33 ppb in one study 20 and above 47 ppb in another 21 were found to predict a good clinical response to ICS in patients with chronic respiratory symptoms.…”

Developments in the field of allergy in 2017 through the eyes of Clinical and Experimental Allergy

“…The second paper conducted a systematic review of 27 studies to assess the diagnostic accuracy of the fraction of NO in exhaled breath. 162 This test, which can be performed using a hand-held monitor, may provide an indicator of eosinophilic inflammation of the airways. Diagnostic accuracy was found to be highly variable, and the results imply that more work is needed using well-designed studies to determine the suitability of this test within the asthma diagnosis pathway.…”

Fatal asthma: Learning from tragedies

“…Exhaled nitric oxide measurements is creeping in as part of the routine care in the asthma clinic . It is therefore important to understand the factors that can change levels, outside of asthma.…”