Fractional exhaled nitric oxide as a biomarker for the evaluating asthmatic patients with allergic bronchopulmonary...

Fractional exhaled nitric oxide (FeNO) is a useful Type 2 biomarker for the diagnosis and management of asthma. Although allergic bronchopulmonary mycosis (ABPM) is an allergic disease characterized by Type 2 inflammation, the clinical significance of FeNO in asthma patients with ABPM has not been well investigated.

The clinical characteristics of patients with and without comorbid ABPM were compared retrospectively using a cohort of patients with asthma. The cut-off values of FeNO for predicting asthma patients with ABPM were examined. We evaluated the associations between FeNO and blood eosinophils, pulmonary function, and mucus plugs.

Of the 177 patients with asthma, 22 had concomitant ABPM. Compared to the group of ashma patient without ABPM, FeNO was significantly higher in the ABPM complicated group. Two FeNO cut-off values were identified for predicting asthma patients with ABPM receiving ICS treatment: 95 ppb was associated with a high certainty for inclusion (sensitivity = 0.27, specificity = 0.97), and 25 ppb with a high certainty for exclusion (sensitivity = 0.82, specificity = 0.39). In asthma patients with ABPM, FeNO correlated with blood eosinophils (r = 0.46, p = 0.03) and mucus plug score (r = 0.508, p = 0.019), but not with percent forced expiratory volume in 1 s (%FEV₁) (r = -0.33, p = 0.18).

Elevated FeNO levels may aid in the detection of ABPM complications in patients with asthma treated with ICS. FeNO levels may be associated with mucus plugging in asthma patients with ABPM.