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.