Abstract
Background’: Fractional exhaled nitric oxide (FeNO) is a quick, accurate, noninvasive tool to detect the measurement of airway inflammation. FeNO is therefore vastly used in the diagnosis and treatment of asthma.
Aim: The purpose of the study is to evaluate and compare the accuracy of spirometry, the asthma control test (ACT), and fractional exhaled nitric oxide in predicting future asthma attacks, as well as their association with each other.
Materials and Methods: Patients with asthma between the ages of 21 to 60 were included. Patients with a smoking history of more than 8 packs per year, as well as, patients in whom spirometry was not recommended were excluded. Fractional exhaled nitric oxide (FeNO) and spirometry were performed on patients who gave their consent to conduct the study. The Asthma Control Test (ACT) questionnaire was used to analyze asthma control. Over the course of the three-month follow-up, several exacerbations were recorded. The effectiveness of FeNO, spirometry, and ACT in predicting exacerbations was compared using the Mann-Whitney test, and the correlation between them was determined using Spearman's correlation coefficient.
Results: Exacerbations occurred in 27% of the 100 trial participants. Patients with and without exacerbations had similar levels of FeNO, according to our research. The median (interquartile range [IQR]) FEV1% in patients with and without exacerbations was 67 (54-78) and 74 (64-87), respectively (P = 0.012). In contrast to those without exacerbations, whose median (IQR) ACT scores were 14 (13-17), patients with exacerbations had a median (IQR) ACT score of 11 (9–15), which was considerably lower (P = 0.002). ACT and FeNO had a poor connection (correlation coefficient: -0.166, P = 0.037). The median (IQR) FeNO level (ppb) was lower in patients taking inhaled corticosteroids (ICS) than in the other group, with values of 21 (13-37) and 29 (16-57), respectively (P = 0.04).
Conclusion: FeNO level and ACT score had an inverse relation. FEV1% and ACT scores were better than FeNO at predicting asthma attacks, as per the research conducted in the present study. The utilization of inhaled corticosteroids caused a drop in FeNO levels.

Key words: Spirometry, fractional exhaled nitric oxide, inhuman led corticosteroid, and asthma control test