Cough is one of the most common symptoms seen in clinical practice, however the differential diagnosis is often difficult. The utility of fractional exhaled nitric oxide (FeNO) measurement in the differential diagnosis of the etiology of cough has been reported. NIOX VERO® (NOV) is a new hand-held device that will replace NIOX MINO®, but its diagnostic utility has not been fully elucidated in clinical practice. In this study, the performance of NOV for FeNO measurements was determined. We retrospectively analyzed 243 consecutive patients complaining cough. Among 243 patients, final diagnosis was cough variant asthma (CVA) in 74 (30.5%), bronchial asthma (BA) in 48 (19.8%), post-infectious cough (PIC) in 52 (21.4%), atopic chough (AC) in 24 (9.9%), gastroesophageal reflux disease (GERD) in 10 (4.1%), and Others in 35 (14.4%). FeNO values were significantly higher in CVA and BA as compared to PIC, AC, GERD, and Others. In the multivariate analysis, only FeNO value was identified as independent factors to discriminate CVA and non-CVA other than BA. These findings indicated that FeNO measured by using NOV could be used as a diagnostic marker of intractable cough, especially for the differential diagnosis of CVA from non-CVA
