The value of nasal nitric oxide measurement in the diagnosis of primary ciliary dyskinesia

IMPORTANCE: Nasal nitric oxide (nNO) testing is a method used in the diagnosis of primary ciliary dyskinesia (PCD). It has not been evaluated in Chinese population. OBJECTIVE: To establish a reference nNO value to assist in the diagnosis of PCD in Chinese children. METHODS: nNO values were measured in children with PCD (n = 36), cystic fibrosis (CF) (n = 20), asthma (n = 45), post‐infectious bronchiolitis obliterans (BO) (n = 41) and non‐PCD/non‐CF bronchiectasis (n = 32). The receiver operating characteristic nNO value for the diagnosis of PCD was plotted and the area under the curve was calculated. RESULTS: nNO values were significantly lower in children with PCD (median 25.66 nL/min) than in children with asthma (186.26 ± 58.95 nL/ min), BO (143.47 ± 49.71 nL/min) and non‐PCD/non‐CF bronchiectasis (173.13 ± 63.80 nL/min), but not in children with CF (90.90 ± 43.20 nL/min). Notably however, no CF patient had an nNO value < 45 nL/min. A cut‐off of 76 nL/min yielded the best sensitivity of 86.1%, and specificity of 91.4%, with an area under the curve of 0.920 (95% confidence interval 0.859–0.981) for the diagnosis of PCD. If CF was ruled out the specificity increased to nearly 100%. INTERPRETATION: nNO testing is able to discriminate between patients with PCD and those with CF, asthma, post‐infectious BO and non‐PCD/non‐CF bronchiectasis. A cut‐off of 76 nL/min could be further examined in patients suspected of PCD, to establish an nNO reference value for PCD screening in Chinese children.