Comparison of fractional exhaled nitric oxide (FeNO) levels measured by different analysers

Abstract

Background: Fractional exhaled nitric oxide (FeNO) is used as a non-invasive marker for asthma diagnosis and management. However, it still remains debatable whether different analysers are comparable to each other. The aim of the present study was to compare FeNO levels obtained by different analysers (NA623NP®, NObreath®, NIOX MINO®, and NIOX VERO®). Methods: For the first study, 153 subjects were enrolled to compare FeNO levels among three different manufactured analysers (NA623NP®, NObreath®, and NIOX MINO®). For the second study, 30 subjects were recruited for comparison of FeNO levels between NIOX MINO® and NIOX VERO®, both of which are manufactured by the same company. In both studies, two repeated FeNO measurements, each using the different analysers, were performed in random order. Results: FeNO levels measured by NIOX MINO® and NObreath® were more variable than NA623NP® although their levels were acceptable. There were strong positive correlations in FeNO levels among these three analysers (p Conclusions: Significant differences in FeNO levels measured by different manufactured analysers should be taken into account in clinical practice although their levels are reproducible.