Predictive meaning of Fractional Exhaled Nitric Oxide (FeNO) in the diagnosis of asthma for epidemiological purposes – an 8-year follow-up study

Abstract Background: Asthma-like symptoms such as dyspnoea, wheezing, and chronic cough are common health problems. Chronic neglected symptoms at the early stages of the disease may herald serious respiratory diseases in the future. On the population level, the respiratory symptoms in children can be estimated via cross-sectional. However, such methods need objective support like the measurement of FeNO. The aim of the study was to analyze if the FeNO value measured at baseline can have predictive meaning for asthma-like symptoms after 8 years of measurement. Methods: The follow-up included 128 (out of 447) children 70 girls and 58 boys. The FeNO was measured at baseline only. The prevalence of asthma-like symptoms was measured with the adopted version of the ISAAC questionnaire. Results: After 8 years from FeNO measurement, 5 new cases of asthma have occurred, 2 cases of attacks of dyspnoea, 1 case of wheezy in the chest, and 18 cases of allergic rhinitis. The FeNO values, measured at the baseline of the study, for new cases of the above diseases, were 53.4±75.9 ppb, 11±1.5 ppb, 12.0 ppb, and 16.3±12.4 ppb, respectively. The best diagnostic accuracy parameters were found in the new cases of asthma where the sensitivity was 40.0%, the specificity was 98.6% and AUC was 66.6% and the diagnostic odds ratio was 46.9 when considering FeNO cut-off >35 ppb.; Conclusions: The FeNO measurement is an objective method for asthma prognosis in early school-aged children with asthma-like symptoms measured on the population level and needs further confirmation on the clinical level with more accurate diagnostic tools.