The FeNO Test

What is the FeNO test?

The FeNO test is a ground-breaking test that helps medics identify which drugs will help individual patients suffering from asthma or Chronic Pulmonary Disease (COPD).

Asthma and COPD affect over six million people in the UK, causing respiratory symptoms such as wheezing, coughing and shortness of breath. While for some it is a mild inconvenience, for others it is life altering and threatening. In fact, 1,200 adults and children in the UK die from asthma attacks each year and, despite the NHS spending more than £1bn a year on treatment, these worrying statistics remain consistent. What’s more, there are 30,000 deaths each year from COPD and alarmingly these have been increasing.

One reason for a lack of progress is asthma has been seen as a single condition; treatment has taken a ‘one size all’ approach. Now, using a combination of two markers of airway inflammation – the FeNO breath test and a readily available blood test – doctors can now stratify patients into different groups and personalise their treatment accordingly.

How does the FeNO test work?

The FeNO breath test measures the levels of nitric oxide in someone’s breath. Nitric oxide is produced by the lining of the airway when it is inflamed and it is a very specific indicator of asthmatic type inflammation called Type 2 inflammation. It therefore helps sign that a patient has inflamed airways and is more likely to have an asthma attack.

The FeNO test uses a hand-held device, similar to a roadside breathalyser:

  • A patient will breathe in through a mouthpiece on the small portable device
  • The air that comes into their lungs has had all the nitric oxide from the environment removed as it goes through the machine
  • The patient will then exhale for 10 seconds, and a minute later, the machine will read what the level of nitric oxide is in their breath
  • Normal oxide concentrations are under 25 parts per billion, so a reading over 50 indicates the patient has Type 2 inflammation

Medics can also use an existing blood count test to give information on the number of eosinophils (inflammation-fighting cells). This is likely to be more useful in older patients where the breath test is less accurate.

What are the benefits of the FeNO test?

The big advantage is that the FeNO test provides very specific evidence into whether a patient’s airways are inflamed and at risk of attack. It is independent of any symptoms and allows for much more precise treatment decisions.

Not only will it help identify those who are likely to respond to steroids; it will also identify the many patients who may be taking treatments that have little gain, but which may have side effects.

The FeNO test is easy to use in primary care and could be incorporated into the asthma checks that are already being performed annually in UK GP surgeries. Both the FeNO breath test and blood test can be used in patients over five years of age.

With instant results, a patient’s medication can be realigned to improve their symptoms, reduce the potential for side effects and provide a more cost-effect approach.

What’s next?

With the FeNO tests now allowing medics to stratify patients, a new class of treatments called biological agents are being revived. Initially trailed in the 1990s, they failed clinical trials as, although they are specifically helpful in patients with high readings of inflammation, they were tested on some patients with Type 2 low asthma. Now that it is possible to identify patients who will benefit from the treatment, the new medications have produced dramatic clinical benefits. It is hoped that these very effective inhibitors will be available in the next few months, and may eventually replace the use of steroids.

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