FENO level greather than 39.5 p.p.b. has 67% sensitivity and 76% specificity for identifying uncontrolled asthma

The fraction of exhaled nitric oxide (FENO) is reduced by anti-inflammatory treatment in asthma. However, some demographic characteristics may cause persistent FENO elevation despite inhaled corticosteroids (ICS) therapy.

This prospective observational study from Japan included 230 patients with stable asthma at baseline. They were evaluated again 3 months later.

A FENO level greater than 39.5 p.p.b. yielded 67% sensitivity and 76% specificity for identifying the patients with poorly controlled asthma.

The persistent high FENO group (higher than 40 p.p.b.) was more likely to have the following characteristics:

- ex-smokers
- atopy (positive specific IgE, higher serum IgE and blood eosinophils)
- allergic comorbidities

Past smoking history, blood eosinophils, and chronic rhinosinusitis were identified to be independent predictors of high FENO.

These results suggested that past smoking history, blood eosinophilia, and chronic rhinosinusitis are involved in the persistent airway inflammation detected by FENO.

This article was included in my monthly review of the top asthma articles at the website of the World Allergy Organization (WAO).

References:

Associated demographics of persistent exhaled nitric oxide elevation in treated asthmatics. Clin Exp Allergy. 2012 May;42(5):775-81. doi: 10.1111/j.1365-2222.2011.03945.x.
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