The alveolar component of exhaled nitric oxide (CalvNO) is associated with the lack of asthma control in patients with mild, untreated asthma, according to research in the Journal of Allergy and Clinical Immunology. The findings support the idea that abnormalities of the peripheral airways are implicated in the mildest forms of asthma, the authors concluded.
For the study, 78 individuals with asthma who had a FEV1 greater than 80% predicted, were not receiving regular treatment, and with no recent exacerbations.
At baseline, asthma control did not correlate with airway obstruction or bronchial NO concentrations. However, there was a significant relationship between ACT score and CalvNO, such that it was significantly higher, at 6.7 ppb, in those with uncontrolled asthma, compared with 4.9 ppb in those with partially controlled or controlled asthma.
Among participants, 55 steroid-naïve patients who began inhaled corticosteroid treatment following baseline assessment showed significant improvement in ACT score at 1 and 3 months, and the level of improvement was significantly associated with baseline CalvNO. Conversely, there was no association between change in ACT score and bronchial NO.
These findings suggest that CalvNO could predict response to inhaled corticosteroid treatment, according to the authors.
“The detection of small airway abnormalities could identify patients at major risk of asthma attacks, or predicts those likely to benefit from a specific intervention,” according to the authors.