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

BACKGROUND

Fractional exhaled nitric oxide (FE) is useful for the evaluation of eosinophilic airway inflammation, including that seen in asthma. Although a new electrochemical hand-held FE 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. The aim of this study was to determine whether there is a difference between the two analyzers.

METHODS

The FE 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 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 level between the NOA280i and the NIOX VERO (r = 0.942, p < 0.001). The following conversion equation was calculated: FE (NOA280i) = 1.362 (SE, 0.661) + 1.384 (SE, 0.021) × FE (NIOX VERO).

CONCLUSIONS

To our best knowledge, we have provided the first report showing that the measured FE 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 Fractional exhaled nitric oxide GINA Global Initiative for Asthma NO Nitric oxide ppb Parts per billion ROC Receiver operating characteristic SD Standard deviation.