Correlation between fractional exhaled nitric oxide level and clinical outcomes among childhood asthmatic patients: community hospital-based perspective

A fractional exhaled nitric oxide (FeNO) device has been developed for the evaluation of clinical control in asthmatic patients, instead of for uses in only analyzing clinical data and spirometry. The implementation of the FeNO device in daily practice has demonstrated both positive and negative results. Community hospital settings in Thailand have never used this method for the evaluation of disease control in asthmatics. The aim of this study was to assess the correlation between FeNO levels and asthma control, as determined by physicians. We recruited asthmatic patients aged from 4-15-years-old (after informed consent approval was obtained from their guardians) from May 15, 2018, to July 20, 2019. All of the patients had already been diagnosed as having asthma by physicians and had been prescribed inhaled corticosteroid medications. After routine visits, skin prick tests with 8 aeroallergens were performed. If a positive result was shown for at least 1 allergen, then the FeNO device was applied for the assessment of the level of inflammation. Data were analyzed by using SPSS Statistics version 21.0. Agreement index and Kruskal Wallis tests were used to measure the correlations. From 178 asthmatic patients, the mean age was 94.9 ± 36.75 months, and 59% of them were male. The educational levels of the guardians of the patients mostly consisted of primary school, and the household income was less than 333 US dollars per month. Inhaled corticosteroids were prescribed among the patients for disease control. The correlation between the FeNO level and the control level demonstrated a high agreement (accuracy index: 91.57%). The medians of the mean wheal diameters of Dermatophagoids pteronyssinus, Dermatophagoids farinae and Cladosporium spp. were significantly related to the FeNO level (with p-values of 0.024, 0.003 and 0.045, respectively). Conversely, a number of positive skin responses to aeroallergens were not related with the FeNO level. In conclusion, a lower level of FeNO correlates with good asthma control level in pediatric allergic asthma. The medians of the mean wheal diameters of Dermatophagoids pteronyssinus, Dermatophagoids farinae and Cladosporium spp. correlated with higher FeNO levels. A device assessing FeNO seems beneficial for evaluating the level of disease control among childhood asthmatic patients in a primary care setting.