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Measuring FeNO

Nurse FeNO testing female patient with NIOX VERO

FeNO can predict the likelihood of steroid responsiveness more consistently than spirometry, bronchodilator response, peak flow variation, or airway hyperresponsiveness to methacholine.1-4

Asthma is often misdiagnosed or under-diagnosed5,6

Obtaining an accurate asthma diagnosis can be a challenge as several diseases present with symptoms similar to asthma.7 Traditional methods of asthma assessment only give part of the picture, as they often do not look specifically at airway inflammation.8

In addition, conventional evaluation methods such as peak flow and spirometry only measure airflow and not airway inflammation specifically. They usually take time to produce results (from few tens of minutes for spirometry to several days for peak flow) and sometimes the results can be difficult to interpret.9 Likewise, symptom assessment can be subjective and lacks sensitivity.4

Therefore, asthma can often be misdiagnosed or under-diagnosed. Studies of patients diagnosed with asthma suggest that up to 33% of adults and 53% of children do not have clear evidence of the condition.5,6 Some may have had asthma in the past, but it is likely that many may have had an incorrect diagnosis.10

FeNO supplements traditional clinical tools

FeNO is a biomarker of Type 2 airway inflammation. FeNO testing is non-invasive and has even shown that it can be more reliable in predicting inflammation and steroid responsiveness than spirometry, bronchodilator response, peak expiratory flow, or airway hypersensitivity.1-4 It enhances the ability of the clinician to make better treatment decisions, avoiding empiric steroid trials and unnecessary long-term treatment.11-15

National and international guidelines on asthma diagnosis and management have been updated in the recent years to include FeNO testing. Guidelines state that a positive FeNO test suggests eosinophilic inflammation and provides supportive evidence for an asthma diagnosis.8-10,16-17

In particular, the guideline on asthma diagnosis and management from the UK’s National Institute for Health and Care Excellence (NICE) endorses the use of FeNO testing in Primary Care, as part of comprehensive diagnostic algorithms for adults, children and young people.10 The health economic model included in the NICE guideline concluded that FeNO testing was the first recommended respiratory test in adults, before spirometry, as the most cost-effective strategy to manage asthma patients.18


References: 1. Knuffman JE, Sorkness CA, Lemanske RF Jr, et al; for the Childhood Asthma Research and Education Network of the National Heart, Lung, and Blood Institute. Phenotypic predictors of long-term response to inhaled corticosteroid and leukotriene modifier therapies in pediatric asthma. J Allergy Clin Immunol. 2009;123:411-416.  2. Szefler SJ, Martin RJ, King TS, et al; for the Asthma Clinical Research Network of the National Heart, Lung, and Blood Institute. Significant variability in response to inhaled corticosteroids for persistent asthma. J Allergy Clin Immunol. 2002;109:410-418.  3. Smith AD, Cowen JO, Brassett KP, et al. Exhaled nitric oxide: a predictor of steroid response. Am J Respir Crit Care Med.2005;172:453-459. 4. Smith AD, Cowan JO, Filsell S, et al. Diagnosing asthma: comparisons between exhaled nitric oxide measurements and conventional tests. Am J Respir Crit Care Med. 2004;169:473-478.  5. Aaron SD et al. Reevaluation of diagnosis in adults with physician-diagnosed asthma. JAMA. 2017 317(3):269-279.  6. Looijmang-van den Akker I et al. Overdiagnosis of asthma in children in primary care: a retrospective analysis. Br J Gen Pract. 2016 66 (644): e152-e157.  7. Morice AH, Fontana GA, Sovijarvi ARA, et al on behalf of the ERS Task Force. The diagnosis and management of chronic cough. Eur Respir J. 2004;24:481-492.  8. Dweik RA, Boggs PB, Erzurum SC, et al; on behalf of the American Thoracic Society Committee on Interpretation of Exhaled Nitric Oxide Levels (FeNO) for Clinical Applications. An official ATS clinical practice guideline: interpretation of exhaled nitric oxide levels (FeNO) for clinical applications. Am J Respir Crit Care Med. 2011;184:602-615.  9. National Asthma Education and Prevention Program; National Heart, Lung, and Blood Institute. Expert panel report 3: guidelines for the diagnosis and management of asthma. Full report 2007.  10. NICE guideline [NG80]: Asthma: diagnosis, monitoring and chronic asthma management. 2017 11. Petsky et al. Exhaled nitric oxide levels to guide treatment for children with asthma. Cochrane Database Syst Rev. 2016 11:CD011439.  12. Petsky et al. Exhaled nitric oxide levels to guide treatment for adults with asthma. Cochrane Database Syst Rev. 2016 11:CD011440.  13. Hanania NA et al. Measurement of fractional exhaled nitric oxide in real-world clinical practice alters asthma treatment decisions. Ann Allergy Asthma Immunol. 2018 120(4):414-418.  14. LaForce C, Brooks E, Herje N, et al. Impact of exhaled nitric oxide measurements on treatment decisions in an asthma specialty clinic. Ann Allergy Asthma Immunol. 2014; 113: 619-623.  15. Hanania NA, Alpan, O, Hamilos, DL et al. Omalizumab in Severe Allergic Asthma Inadequately Controlled With Standard Therapy. Ann Intern Med. 2011;154:573-582.  16. GINA-Global Strategy for Asthma Management and Prevention, Global Initiative for Asthma (GINA). 2018 17. British Thoracic Society. British guideline on the management of asthma: A national clinical guideline, 2016. 18. NICE Diagnostics guidance [DG12]: Measuring fractional exhaled nitric oxide concentration in asthma: NIOX MINO, NIOX VERO and NObreath. 2014