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National and international guidelines for FeNO testing

FeNO testing is becoming increasingly important and can be used regularly to improve patient outcomes.1 Most national and international societies today recommend FeNO and emphasise the value of FeNO testing for more accurate diagnosis and better asthma management.1-7 The American Thoracic Society, the European Respiratory Society, the Global Initiative for Asthma, the National Heart, Lung, and Blood Institute in the US, and the National Institute for Health and Care Excellence in the UK have recently updated their guidelines. This article provides a helpful overview of the main recommendations for FeNO testing.

Many studies have shown that FeNO testing can assist in asthma diagnosis, predict response to inhaled corticosteroids (ICS), optimise therapy, monitor adherence and reduce exacerbations by up to 50%.8,9 This can be done in one quick test, right at the point-of-care.10 Therefore, FeNO levels must be measured correctly and the results carefully interpreted. Recently updated guidelines aim to guide healthcare professionals through this process.

FeNO in the guidelines

Nowadays, most guidelines emphasise the added value of FeNO testing for asthma diagnosis and management.1-7

The American Thoracic Society (ATS) was the first society to recognise the broad range of clinical benefits of FeNO testing in 20112 and published the widely used cut-off points for the interpretation of results. Low FeNO values (≤25 ppb for adults, ≤20 ppb for children under 12 years of age) indicate that Type 2 inflammation and responsiveness to corticosteroid treatment are unlikely.2 High FeNO levels (≥50 ppb for adults, ≥35 ppb for children under 12 years of age) point in the opposite direction, suggesting Type 2 inflammation and response to corticosteroids are likely.2 The ATS strongly recommends that healthcare professionals use FeNO testing to help diagnose Type 2 inflammation and predict the likelihood of steroid responsiveness.2 Regular FeNO tests to monitor airway inflammation in asthma patients are also strongly recommended.11 In 2021, the ATS published a new guideline, recommending FeNO testing should be incorporated in usual care when treating asthma patients.1

In 2021 and 2022, the European Respiratory Society (ERS) published its first guidelines on the diagnosis of asthma in children and adults.3,4 Professor Erol Gaillard led the work on the paediatric guideline. The group agreed to recommend FeNO testing as a first-line test to diagnose asthma in children.3 In the adult guideline, led by Professor Renaud Louis, FeNO testing is recommended as part of the diagnostic work-up if there is uncertainty after spirometry and bronchodilator reversibility testing.4 The ERS has not yet released guidelines on the management of mild to moderate asthma but did publish a joint guideline with the ATS in 2020, recommending the use of FeNO in severe asthma to identify patients appropriate for biologic treatment, as well as to select the right biologic.12

The NG80 guideline published in 2021 by the National Institute for Health and Care Excellence (NICE) in the UK also focuses on the diagnosis of asthma.5 The recommendations are very similar to those of the ERS. NICE recommends performing FeNO testing in all adults when an asthma diagnosis is suspected, and suggests considering FeNO testing in children (5 to 17 years of age) if the diagnosis is still uncertain after initial assessment.5 NICE also recommends using FeNO testing to manage patients who are symptomatic despite ICS.5 The institute recommends using 40 ppb as a single cut-off to determine the likelihood of airway inflammation.5

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In the US in 2020, the National Heart, Lung, and Blood Institute (NHLBI) published a focused update of its 2007 asthma guidelines.6 This update addresses six important areas, including FeNO testing. The NHLBI recommends adding FeNO testing to the diagnostic work-up in both adults and children if the asthma diagnosis is uncertain after initial assessment or if spirometry cannot be performed.6 The institute also recognised the value of FeNO testing in asthma management, and recommends FeNO to help select and manage ICS therapy.6 The Global Initiative for Asthma (GINA) has included FeNO testing in its guidelines for many years, especially in the severe asthma treatment algorithm.7 GINA lists FeNO as one of the biomarkers for assessing the severe asthma phenotype.7 In addition, GINA recognises FeNO as a predictor of good response to certain biologics: FeNO levels greater than 20 ppb indicate a good response to anti-IgE and levels above 25 ppb suggest a patient will respond well to dupilumab

In 2023, Deutsche Gesellschaft für Pneumologie und Beatmungsmedizin (DGP) published an updated S2k Guideline for Specialist Diagnosis and Therapy of Asthma to include new evidence on the importance of type 2 biomarkers, which includes FeNO. The authors note that FeNO is a quick and reproducible test that’s easy to perform, with elevated FeNO values showing a correlation to type 2 airway inflammation. They highlight that FeNO is important in the diagnosis and phenotyping of asthma, as well as for therapy planning and control. They conclude that measuring FeNO is an important component in the diagnosis and management of asthma, and is an indispensable diagnostic tool in pneumology-specialist care.

An image of the front cover of the interpretation of FeNO levels with NIOX VERO® document

Access our guide for the interpretation of FeNO levels with NIOX VERO®.


The role of NIOX® in the creation of the guidelines

NIOX® has been the FeNO technology of choice in the vast majority of clinical trials since its invention in 1999.13 For example, in the studies analysed by the ATS to define the widely used limits of 25 ppb and 50 ppb, FeNO measurements were performed on 83% of patients with NIOX® devices.14

NIOX VERO® has been proven to be reproducible, reliable and easy to use.10 As the device requires minimal training for the operator, and provides a simple test for patients to perform10, NIOX VERO® is a convenient addition to FeNO testing in the clinical setting.

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13. Data on File; C-NIOX-0004
14. Data on File; C-NIOX-0001