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

Abstract Background: Fractional exhaled nitric oxide (FENO) is useful for the evaluation of eosinophilic airway inflammation, including that seen in asthma. Although a new electrochemical hand-held FENO 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 FENO. The aim of this study was to determine whether there is a difference between the two analyzers. Methods: The FENO 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 FENO 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 FENO level between the NOA280i® and the NIOX VERO® (r = 0.942, p < 0.001). The following conversion equation was calculated: FENO (NOA280i®) = 1.362 (SE, 0.661) + 1.384 (SE, 0.021) × FENO (NIOX VERO®). Conclusions: To our best knowledge, we have provided the first report showing that the measured FENO 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. AbbreviationsATS American Thoracic SocietyBMI Body mass indexERS European Respiratory SocietyFENO Fractional exhaled nitric oxideGINA Global Initiative for AsthmaNO Nitric oxideppb Parts per billionROC Receiver operating characteristicSD Standard deviation