Fractional exhaled nitric oxide, a potential biomarker for evaluating glucocorticoids treatment and prognosis in allergic bronchopulmonary aspergillosis

Background Allergic bronchopulmonary aspergillosis (ABPA) is characterized by enhanced Th2 inflammatory response. Fractional exhaled nitric oxide (FeNO) measurement has been utilized as a valuable tool in predicting the development and management of asthma, another typical Th2 inflammation. However, the clinical significance of FeNO in ABPA remains unclear. Objective To investigate the association between FeNO and the prognosis of ABPA patients, so as to provide a basis for the use of FeNO in evaluating the efficacy of glucocorticoids in ABPA treatment. Methods This study consists of two parts. 58 patients were enrolled in the retrospective study. Clinical indexes between patients with different prognoses were compared and ROC curve analysis were employed to determine the threshold value. The prospective observational study involved 61 patients who were regularly followed up at 4-6 weeks and 6 months since the initial treatment. Patients were grouped based on baseline FeNO values, correlation analysis were performed between clinical data. Results Different prognoses were observed between patients with High- and Low- baseline FeNO values, with a threshold value of 57 ppb. The percentage of A. fumigatus-specific IgE, percentage of positive A. fumigatus-specific IgG, and relapse/exacerbation rate differed significantly between the H/L-FeNO groups. Patients with higher FeNO needed longer treatment duration and showed shorter interval between glucocorticoid withdrawal and the next relapse/exacerbation. Conclusion Our findings indicate that the level of FeNO is associated with the prognosis of ABPA. It can serve as an independent and valuable biomarker for evaluating the effectiveness of glucocorticoid treatment.