Department of Preventive and Social Medicine, Dunedin School of Medicine, University of Otago, New Zealand.
Respir Med. 2011 Nov;105(11):1629-34. doi: 10.1016/j.rmed.2011.06.001.
Constitutional factors such as age, sex and height, and acquired factors such as atopy and smoking, influence exhaled nitric oxide (F(E)NO) levels. The utility of predicted values based on reference equations which account for these factors has not been evaluated.
To compare the performance characteristics of absolute versus % predicted values for F(E)NO as predictors of diagnosed asthma and steroid response.
We compared the sensitivities, specificities and likelihood ratios using F(E)NO (% predicted) with absolute values for F(E)NO (ppb) in 52 steroid-naive subjects with non-specific respiratory symptoms. The reference equations of Olin et al. (Chest, 2007) and Dressel et al. (Resp. Med., 2008) were used to derive predicted values. Receiver operating curve analyses were performed and the areas under the curve (AUC) were calculated for two outcomes: diagnosed asthma (yes/no), and steroid response after fluticasone for 4 weeks (defined as ≥ 12% increase in FEV(1); increase in mean morning PEF ≥ 15%; reduction in symptoms ≥ 1 point; increase in PC(20)AMP of ≥ 2 doubling doses).
The AUCs for diagnosed asthma were: F(E)NO (absolute) 0.770; F(E)NO (% pred.): 0.758 (Olin) and 0.775 (Dressel) (NS). The AUCs for F(E)NO (abs.) and F(E)NO (% pred.) with respect to the four indices of steroid response were likewise not significantly different.
Correcting F(E)NO for combinations of age, sex, height, smoking and atopy using reference equations did not enhance the performance characteristics of F(E)NO as a predictor of either the diagnosis of asthma or steroid responsiveness in patients with chronic airways-related symptoms.
影响呼出气一氧化氮（F（E）NO）水平的因素包括固有因素，如年龄、性别和身高，以及获得性因素，如特应性和吸烟。尚未评估基于考虑这些因素的参考方程预测值的效用。
比较 F（E）NO 的绝对值与 %预测值作为诊断哮喘和类固醇反应预测指标的性能特征。
我们比较了 52 例非特异性呼吸道症状的类固醇初治患者中，使用 F（E）NO（%预测值）与 F（E）NO（ppb）绝对值的敏感性、特异性和似然比。使用 Olin 等人的参考方程（Chest，2007 年）和 Dressel 等人的参考方程（Resp. Med.，2008 年）来推导预测值。进行了受试者工作特征曲线分析，并计算了两个结果的曲线下面积（AUC）：诊断性哮喘（是/否）和氟替卡松治疗 4 周后的类固醇反应（定义为：FEV1 增加≥12%；平均晨峰 PEF 增加≥15%；症状减少≥1 分；PC20AMP 增加≥2 倍剂量）。
诊断性哮喘的 AUC 为：F（E）NO（绝对值）为 0.770；F（E）NO（%预测值）：0.758（Olin）和 0.775（Dressel）（无统计学差异）。F（E）NO（绝对值）和 F（E）NO（%预测值）与类固醇反应四项指标的 AUC 也无显著差异。
使用参考方程校正年龄、性别、身高、吸烟和特应性等因素对 F（E）NO 的影响，并未提高 F（E）NO 作为慢性气道相关症状患者哮喘诊断或类固醇反应性预测指标的性能特征。
