Department of Respiratory Diseases, The Affiliated Hospital of Guizhou Medical University, Guiyang, Guizhou, PR China.
Department of Respiratory Diseases, West China School of Medicine & West China Hospital, Sichuan University, Chengdu, Sichuan Province, PR China.
Indian J Med Res. 2018 Oct;148(4):441-448. doi: 10.4103/ijmr.IJMR_1478_16.
BACKGROUND & OBJECTIVES: The diagnostic value of fractional exhaled nitric oxide (FeNO) in patients with asthma remains controversial. This study was aimed to re-evaluate the diagnostic value of FeNO in specific groups with asthma and identify potential factors associated with FeNO.
FeNO measurement and bronchial provocation test (BPT) or bronchodilator test (BDT) were performed in patients with suggestive symptoms for asthma. Correlation analysis was performed, and receiver-operating characteristic (ROC) curves and area under the curve (AUC) were calculated to evaluate the accuracy of FeNO in diagnosis.
A total of 265 (66.3%) patients with asthma were identified in 400 individuals suspected to have asthma from October 2014 to June 2015. Positive correlations of gender (r=0.138, P=0.005), atopy (r=0.598, P <0.001) and rhinitis (r=0.485, P <0.001) but negative correlations of age (r=-0.220, P <0.001) and the cumulative methacholine dosage with a 20 per cent decrease in forced expiratory volume in one second (r=-0.197, P <0.001) with FeNO were found. AUC of FeNO in whole population and patients with atopy and rhinitis was 0.728 [95% confidence interval (CI) 0.675-0.781, P <0.001] and 0.752 (95% CI 0.640-0.865, P <0.001), while the cut-offs were 23.5 and 44.5 parts per billion (ppb), respectively, rendering sensitivities, specificities, positive predictive value and negative predictive value of 79.9, 54.7, 77.9, 58.1 and 78.7, 67.9, 89.2 and 48.7 per cent, respectively. The cut-off of FeNO with specificity of 90 per cent (FeNO) for all patients and a sub-group of patients with atopy and rhinitis was 59.5 and 90.5 ppb, respectively, while FeNOdecreased by 12 ppb with every 10 years.
INTERPRETATION & CONCLUSIONS: : Our findings show that the diagnostic value of FeNO varies in different groups of patients with asthma, thus, the cut-off point should be adjusted in different asthmatic sub-populations. A cut-off point of FeNO with a specificity >90 per cent could decrease the false-positive rate.
呼出气一氧化氮（FeNO）在哮喘患者中的诊断价值仍存在争议。本研究旨在重新评估 FeNO 在哮喘特定人群中的诊断价值，并确定与 FeNO 相关的潜在因素。
对 2014 年 10 月至 2015 年 6 月间疑似哮喘的 400 例患者进行 FeNO 测量和支气管激发试验（BPT）或支气管扩张剂试验（BDT）。进行相关性分析，并计算受试者工作特征（ROC）曲线和曲线下面积（AUC），以评估 FeNO 在诊断中的准确性。
共发现 400 例疑似哮喘患者中有 265 例（66.3%）哮喘患者。性别（r=0.138，P=0.005）、特应性（r=0.598，P<0.001）和鼻炎（r=0.485，P<0.001）与 FeNO 呈正相关，而年龄（r=-0.220，P<0.001）和累积乙酰甲胆碱剂量与一秒用力呼气量下降 20%（r=-0.197，P<0.001）与 FeNO 呈负相关。FeNO 在整个人群和特应性和鼻炎患者中的 AUC 为 0.728 [95%置信区间（CI）0.675-0.781，P<0.001]和 0.752（95%CI 0.640-0.865，P<0.001），截断值分别为 23.5 和 44.5 皮克/每十亿（ppb），分别具有 79.9%、54.7%、77.9%、58.1%和 78.7%、67.9%、89.2%和 48.7%的敏感性、特异性、阳性预测值和阴性预测值。FeNO 特异性为 90%（FeNO）的所有患者和特应性和鼻炎患者亚组的截断值分别为 59.5 和 90.5 ppb，而每增加 10 年，FeNO 降低 12 ppb。
我们的研究结果表明，FeNO 在不同哮喘患者群体中的诊断价值存在差异，因此，应在不同的哮喘亚人群中调整截断值。FeNO 特异性>90%的截断值可降低假阳性率。
