The measurement of exhaled nitric oxide (eNO) is a noticeable tool that reflects asthmatic airway inflammation. However, the eNO values might be variable according to the patient's condition and the method of measurement. The aim of this study was to compare the values of eNO measured by two different eNO analyzers in asthmatic children (Niox mino® [Aerocrine; Solna, Sweden] and CLD88® [Eco Medics; Durten, Switzerland].
One hundred four asthmatic children and 59 healthy controls were enrolled. The study participants underwent pulmonary function testing before and after inhaled bronchodilator treatment, a methacholine provocation test, and sputum induction; the eNO concentration was then measured.
The value of eNO measured by Niox mino® was significantly lower than the value of eNO measured by CLD88® (30.7±25.0 vs. 38.6±29.2 ppb, P<0.001). The intraclass correlation coefficient was 0.786 (P<0.001). The eNO concentration was significantly increased in asthmatic children than controls (38.4±27.9 vs. 17.2±9.0 ppb, P <0.001 by Niox mino®; 47.8±31.8 vs. 22.2±12.7 ppb, P<0.001 by CLD88®). The eNO concentration was significantly correlated with the FEV1/FVC (r=-0.382, P<0.001 [Niox mino®]; r=-0.273, P=0.001 [CLD88®], percent sputum eosinophils (r=0.257, P=0.032 [Niox mino®]; r=0.297, P=0.017 [CLD88®]), and PC20 (r=-0.333, P<0.001 [by Niox mino®] r=-0.240, P=0.003 [CLD88®]).
The measurement of eNO might be a supportive tool for the diagnosis of asthma in children; however, the eNO values differ according to analyzers.