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Using FeNO testing to reduce asthma exacerbations.

Good control of asthma exacerbations benefits both patients and healthcare providers. Recent studies show that introducing FeNO (fractional exhaled nitric oxide) testing to overall asthma management is an effective way to reduce recurring exacerbations.1-3

Asthma exacerbations cause anxiety to patients as well as to their families and friends. It also puts stress on an already overburdened healthcare system, especially during periods when airway and lung-related conditions peak in their exacerbation incidence rates. This article examines FeNO testing and asthma exacerbations.

Exacerbation rate reduced by almost 50% (2013)

In 2013, a randomised trial aimed to test if FeNO would lead to reduced exacerbations and improve asthma management in primary care. 187 non-smoking asthma patients (18-64 years) with perennial allergy who received regular ICS treatment were randomly assigned to two groups and followed up for 1 year. The results showed that FeNO testing reduced the exacerbation rate by almost 50%.1

The effect was most visible in moderate rather than severe exacerbations. A possible explanation is that moderate exacerbations are often related to allergen exposure, which is something that FeNO testing detects at an early stage.1

Significant reduction of exacerbations (2016)

In 2016, Cochrane performed a systematic meta-analysis of the published data looking at FeNO testing and asthma exacerbation rates. 7 RCTs were chosen, where 1,546 adults participated in the study for a duration of between four and twelve months.2

The analysis found that treatment decisions that took FeNO levels into account led to a significant reduction in the number of exacerbations, compared with the control group. Those in the FeNO group were also significantly more likely to have a lower exacerbation rate.2

An Adult performing a FeNO test on a NIOX VERO®.

An Adult performing a FeNO test on a NIOX VERO®.

Cochrane published a similar analysis the same year, this time looking at FeNO utility in asthma exacerbations among children with the mean age of 10-14 years. There were 9 RCTs included with 1,426 participants, over a 6-12 months study period. The occurrence of one or more asthma exacerbations was significantly lower in the FeNO group vs. control. The number of children in the FeNO group requiring oral corticosteroid courses was significantly lower in comparison to the children in the control group (OR 0.63, 95% CI 0.48 to 0.83; 1169 participants; 7 studies where p=0.001).3

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Identifying asthma patients at risk (2018)

An observational study, carried out in 2018, involved 337 respiratory specialists and 7,901 asthma patients. The clinicians made an initial assessment and kept track of their original treatment plans before and after FeNO testing. Their records show that after FeNO measurement, they made changes to their treatment plan in 31% of cases, and prescriptions for corticosteroids were adjusted in 90% of cases.4

The study concludes that FeNO monitoring can help to identify patients who are at risk of future exacerbations, including those who may not be identified by traditional methods.4


Asthma is a complex condition and it is in everyone’s interest to establish routines that improve control of asthma exacerbations. The results of these studies demonstrate that FeNO testing can help to reduce both the number and the severity of exacerbations. This is very positive for patients and their relatives, as well as for healthcare providers.

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1 Syk J et al. Anti-inflammatory treatment of atopic asthma guided by exhaled nitric oxide: a randomized, controlled trial. J Allergy Clin Immunol Pract. 2013 1(6):639-48.
2. Petsky et al. Exhaled nitric oxide levels to guide treatment for adults with asthma. Cochrane Database Syst Rev. 2016 11:CD011440.
3. Petsky et al. Exhaled nitric oxide levels to guide treatment for children with asthma. Cochrane Database Syst Rev. 2016 11:CD011439.
4. 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.