Value of nasal nitric oxide in the diagnosis of primary ciliary dyskinesia
The aim of this study is to report nasal nitric oxide (nNO) values in children with primary ciliary dyskinesia (PCD) and to compare them with nNO values in healthy children, asthmatic children, children with cystic fibrosis and children with post infectious bronchiectasis. We determined nNO values in 9 children with PCD, 36 asthmatic children, 31 children with cystic fibrosis, 8 children with post infectious bronchiectasis and 37 healthy children. We compared nNO values between these different conditions and calculated sensitivity and specificity of nNO to diagnose PCD. All children with PCD - except one (nNO 348 ppb) - had nNO values below 112 ppb, mean 88 ppb (95%CI 9.6-166). The nNO mean was 898 ppb (95%CI 801-995) in healthy children, 1023 ppb (95%CI 911-1137) in asthmatic children, 438 ppb (95%CI 367-508) in cystic fibrosis children and 361 ppb (95%CI 252-470) in children with post infectious bronchiectasis. The mean concentration of nNO was lower (P<0.05) in PCD patients, compared to the other groups. The measurement of nasal NO in our study population showed, at a cut-off level of < or =112 ppb, a sensitivity of 88.9% and a specificity of 99.1% in the diagnosis of PCD [ROC 0.98 (95%CI 0.94-0.99); P<0.0001; probability ratio 95.1]. The measurement of nasal NO appears to be a useful tool for screening children for PCD, in which a cut-off level of < or =112 ppb suggests the disease, although nNO above 112 ppb does not exclude PCD.