GPs are to be encouraged to use nitric oxide breath tests to help diagnose and manage asthma, under plans unveiled in new draft guidance from NICE.
The proposed diagnostic guidance recommends testing exhaled nitric oxide concentrations – or fractional exhaled nitric oxide (FeNO) – along with other clinical tests, to help confirm a diagnosis of eosinophilic asthma in both children and adults.
The guidance also recommends FeNO testing to help guide asthma management in patients who remain symptomatic despite taking inhaled corticosteroids (ICS), on the basis it could help doctors to check whether patients are adhering to treatment and reduce their risk of exacerbations.
NICE said achieving an accurate diagnosis of asthma is often complicated and can take many years, and that FeNO testing ‘improved the accuracy of diagnosis when used in addition to other tests’, although it cautions the test is only suitable for ‘ruling in’ rather than excluding asthma.
The guidance specifically advises FeNO testing ‘as an option to help with diagnosing asthma in adults and children who, after initial clinical examination, are considered to have an intermediate probability of having asthma (as defined in the British guideline on the management of asthma, 2012) and when bronchodilator reversibility testing is intended’.
The diagnostics advisory committee said measurement of FeNO, along with bronchodilator reversibility testing, can be done in primary care and therefore offers a cost-effective alternative to approaches that require tests to be done in secondary care.
The committee also agreed FeNO testing is ‘a useful marker to measure whether people use their medicines as agreed with their clinician’ and ‘could be a useful tool for doctors to improve concordance, by which the patient and clinicians make decisions together about their treatment’. Currently, around 30% of patients do not take ICS for asthma control as prescribed.
However, the committee warned FeNO levels should not be used as a basis for stepping down treatment in patients with well-controlled asthma, because the potential risks of under-treatment outweigh the benefits.
The draft states: ‘The committee concluded that FeNO measurement should not be recommended to help with stepping down ICS use in adults or children whose asthma is well managed.
‘However, it considered FeNO measurement to be cost and clinically effective when used as an option to support symptomatic asthma management in people using inhaled corticosteroids.’
The new advice marks a significant shift on FeNO testing since the most recent British guideline on the management of asthma developed by SIGN experts, which concluded protocols for FeNO testing in diagnosis and monitoring ‘have not been well defined and more work is needed’.
NICE draft diagnostic guidance on breath tests for asthma – key points
1. Fractional exhaled nitric oxide (FeNO) testing is recommended as an option to help with diagnosing asthma in adults and children:
- who, after initial clinical examination, are considered to have an intermediate probability of having asthma (as defined in the British guideline on the management of asthma, 2012) and
- when bronchodilator reversibility testing is intended.
Further investigation is recommended for people whose FeNO test result is negative, because a negative result does not exclude asthma.
2. FeNO measurement is recommended as an option to support asthma management (in conjunction with the British guideline on the management of asthma, 2012) in people who are symptomatic despite using inhaled corticosteroids.
- Three commercial devices covered: NIOX MINO, NIOX VERO and NObreath
- Cut-offs of between 47 and 76 parts per billion (ppb) should be used in adults and 30 to 55 ppb in children
- FeNO levels above these cut-offs diagnose asthma with 88–100% specificity in adults and 92–100% specificity in children