Difference between two exhaled nitric oxide analyzers, NIOX VERO® electrochemical hand-held analyzer and NOA280i® chemiluminescence stationary analyzer.

Background: Fractional exhaled nitric oxide (FE_NO) is useful for the evaluation of eosinophilic airway inflammation, including that seen in asthma. Although a new electrochemical hand-held FE_NO analyzer, the NIOX VERO^® (Aerocrine AB, Solna, Sweden), is clinically convenient to use, it has not been fully compared with the chemiluminescence stationary electrochemical analyzer NOA280i^® (Sievers Instruments, Boulder, CO, USA) in terms of the level of measured FE_NO. The aim of this study was to determine whether there is a difference between the two analyzers. Methods: The FE_NO levels measured with both NIOX VERO^® and NOA280i^® were evaluated in 1,369 adults at Juntendo University Hospital from May 2016 to October 2016. Results: The median FE_NO level measured with the NIOX VERO^® was significantly lower than that measured with the NOA280i^® (41 ppb, range 5-368 ppb vs. 29 ppb, range 5-251 ppb; p < 0.001). There was a strong positive correlation in the measurement of FE_NO level between the NOA280i^® and the NIOX VERO^® (r = 0.942, p < 0.001). The following conversion equation was calculated: FE_NO (NOA280i^®) = 1.362 (SE, 0.661) + 1.384 (SE, 0.021) × FE_NO (NIOX VERO^®). Conclusions: To our best knowledge, we have provided the first report showing that the measured FE_NO level with the NIOX VERO^® was approximately 30% lower than that with the NOA280i^® and that there was a significant correlation between the measurements of these two devices. The correction equation that we provided may help assess the data obtained by these two analyzers. Abbreviations: ATS American Thoracic Society BMI Body mass index ERS European Respiratory Society FE_NO Fractional exhaled nitric oxide GINA Global Initiative for Asthma NO Nitric oxide ppb Parts per billion ROC Receiver operating characteristic SD Standard deviation [ABSTRACT FROM AUTHOR]