Asthma UK Centre for Applied Research

Project: DEFINE

Development and Evaluation of an online FeNO-guided asthma management INtervEntion in primary care

Around 5.4 million people in the UK receive treatment for asthma. However, although more and more asthma medications are being prescribed each year, numbers of serious asthma attacks are not going down. To help prevent serious asthma attacks, we need to make sure the right treatments are given to the right people in the right amounts. A breath test called fractional exhaled nitric oxide (FeNO) can help us do this by telling us how much inflammation (swelling) there is in someone’s airways.

The DEFINE study will help health care professionals in GP surgeries provide a more personalised approach to managing patients’ asthma by using FeNO to guide decisions about their treatment.

We are working with GP Practices to invite asthma patients to have a FeNO test during their asthma review, and then tell us what it was like. This will help us understand how to best support patients and healthcare professionals to use FeNO testing to support better asthma management.


Our intervention involves a simple breath test to measure FeNO. Patients with a higher FeNO have more inflammation in their airways. These patients are more likely to have an asthma attack if their inflammation remains untreated. FeNO is already measured in patients with severe asthma who are seen in hospital clinics. However, very few GP surgeries routinely use FeNO to help them monitor treatment.

We are designing an intervention to support health care professionals and patients in using FeNO during asthma reviews in primary care. The intervention will offer the following tools:

  • An online training tool to support health care professionals in how to measure and interpret FeNO.
  • A digital FeNO-guided management algorithm to personalise asthma care.
  • Information materials for patients on FeNO and its role in asthma management.

Find out more about the study and how you could take part on the main DEFINE website from the University of Oxford.

The DEFINE Study 

Key People

Professor Mike Thomas

Mike Thomas

Kay Wang

Kay Wang

Co-lead Co-lead and NIHR Postdoctoral Fellow
Based at: University of Southampton Based at: University of Oxford
Mike's Profile Kay's Profile


February 2020 - February 2025

Contact us

Email the DEFINE Study team



The DEFINE study is funded by the National Institute for Health Research (NIHR) under its Programme Grants for Applied Research Programme (Grant Reference RP-PG-0618-20002).