Third Department of Internal Medicine, Wakayama Medical University, School of Medicine, Japan.
Allergol Int. 2011 Sep;60(3):331-7. doi: 10.2332/allergolint.10-OA-0277. Epub 2011 Apr 25.
Measurement of the exhaled nitric oxide fraction (FE(NO)) has been proposed as a useful diagnostic test for asthma. However, most of the data concerning the FE(NO) cutoff values for the diagnosis of asthma have not yet examined using standard procedures. Furthermore, there is no detailed study that investigated the cutoff values that takes into account patient factors that influence the FE(NO) levels.
FE(NO) was measured in 142 steroid-naive asthmatics and 224 control subjects using an online electrochemical nitric oxide analyzer in accordance with the current guidelines. Subjects without respiratory symptoms and normal spirometric parameters were included in the control group. Asthma was diagnosed on the basis of the presence of significant airway reversibility and/or airway hyperresponsiveness during clinical follow up 6 months after FE(NO) measurements.
FE(NO) was significantly higher in asthmatic patients compared with control subjects (p < 0.01). Based on all study subjects, the receiver operating characteristic curves indicated that the cutoff value of FE(NO) 22 parts per billion (ppb) was associated with the highest combination of sensitivity (90.8%) and specificity (83.9%). Multivariate analysis showed allergic rhinitis, current smoking, and asthma were significant factors influencing the FE(NO) levels. The cutoff values of FE(NO) to discriminate asthma from non-asthma ranged from 18 to 28 ppb depending on rhinitis and smoking status.
The cutoff values presented may be useful for the interpretation of FE(NO) values in the clinical practice.
呼气一氧化氮分数（FE（NO））的测量已被提议作为一种有用的哮喘诊断测试。然而，关于用于诊断哮喘的 FE（NO）截断值的数据尚未使用标准程序进行检查。此外，没有详细的研究调查考虑影响 FE（NO）水平的患者因素的截断值。
根据当前指南，使用在线电化学一氧化氮分析仪测量了 142 名未经类固醇治疗的哮喘患者和 224 名对照受试者的 FE（NO）。在对照组中，包括没有呼吸道症状和正常肺功能参数的受试者。哮喘是根据临床随访 6 个月后 FE（NO）测量期间存在明显的气道可逆性和/或气道高反应性而诊断的。
哮喘患者的 FE（NO）明显高于对照组（p < 0.01）。基于所有研究对象，受试者工作特征曲线表明，FE（NO）22 个部分每十亿（ppb）的截断值与最高的敏感性（90.8%）和特异性（83.9%）相结合。多变量分析显示过敏性鼻炎、当前吸烟和哮喘是影响 FE（NO）水平的重要因素。根据鼻炎和吸烟状况，FE（NO）的截断值从 18 到 28 ppb 不等，可用于区分哮喘和非哮喘。
提出的截断值可能有助于在临床实践中解释 FE（NO）值。
