To assess the diagnostic value of fractional exhaled nitric oxide (FENO) in mild asthma.<h4 class="h4">Material and methodsh4>
Cross-sectional descriptive study in a group of patients with no history of respiratory or allergic illness (control group) and a group of patients with a history of mild asthma with no baseline treatment (asthma group), both aged 6 to 14 years. The following examinations were performed: measurement of FENO using the portable NIOX MINO庐 device, allergy tests and spirometry. Repeatability of paired FENO measurements was estimated with the intraclass correlation coefficient, the repeatability coefficient and the variation coefficient. The diagnostic value was assessed with the sensitivity, specificity, area under the ROC curve and positive likelihood ratio (LR+) for each cut-off point.<h4 class="h4">Resultsh4>
Eighty-seven patients were included in the control group and 57 in the asthma group. The mean FENO value was 12.1 ppb (SD 13.5) in the control group and 42.9 ppb (SD 24.5) in asthmatics (
The determination of FENO with NIOX MINO庐 has an adequate repeatability, especially for healthy patients. For asthmatic patients we recommend determining the average of two measurements. The test has a high diagnostic value in mild asthma. Subclinical sensitisation to pneumoallergens can cause the FENO value to rise to pathologic levels.