Diagnostic cutoff values for portable nasal nitric oxide test in patients with primary ciliary dyskinesia

<bold>Introductions:</bold> Primary ciliary dyskinesia(PCD) is a rare genetic disease that is diagnosed based on clinical findings, transmission electron microscopy(TEM), genetic testing, nasal nitric oxide test(nNO), high-speed video microscopy analysis, and functional analysis of ciliary movement. According to PCD diagnostic standards, the nNO test is less than 77 nL/min using a chemiluminescence analyzer, but this machine is expensive and difficult to use in actual clinical practice. <bold>Aims:</bold> In this study, we sought toinvestigate the diagnostic cut off value of the portable nNO device in a group of patients diagnosed with PCD and a control group. <bold>Materials and Methods:</bold> In patients diagnosed with PCD, nNO testing was performed using the NIOX VEROⓇ device using tidal breathing. Subjects were tested at least twice to compare the PCD patient group and control group. <bold>Results:</bold> There were a total of 8 PCD patients diagnosed, the nNO test result was 47.9±31.2 ppb (4-127ppb). The healthy control group was 15 people, and the nNO test result was 484.8±225.8 ppb (253-1127). There were a total of 10 people in the allergic disease group, the nNO test result was an average of 455±205.6 ppb (226-909) (P<0.001). The maximum point of the youden index (sensitivity +specificity-), which reflects the sum of sensitivity and specificity, was 177 ppb, and the youden index was 0.944. In the ROC curve showing the relationship between PCD diagnosis and nNO value, the AUC was 0.973. <bold>Conclusions:</bold> The portable nNO test can be useful in diagnosing PCD, and a diagnostic standard (cut-off) for the nNO test using an electrochemical device with high sensitivity and specificity will be needed.