过敏史减弱呼出气一氧化氮对慢性咳嗽患者痰嗜酸性粒细胞的预测作用

History of atopy reduces predictive value of fractional exhaled nitric oxide for eosinophilic airway inflammation in chronic cough

目的 探讨过敏史对呼出气一氧化氮预测慢性咳嗽患者痰嗜酸粒细胞价值的影响。方法 收集南方医科大学南方医院呼吸科门诊2016年11月-2021年10月超过3周主诉为咳嗽的病人共868例,包括亚急性咳嗽119例,慢性咳嗽749例,排除肺部感染,3-8周之间的咳嗽定义为亚急性咳嗽,超过8周定义为慢性咳嗽。应用受试者工作特性曲线(ROC)分析呼出气一氧化氮(FENO)的预测值,应用曲线下面积评价FENO的预测准确性。采用患者就诊记录中所记载的过敏史、花粉过敏、动物(皮毛)过敏史或食物过敏史来确定患者的过敏状态。结果 共纳入868名患者,其中173名患者(19.9%)患有嗜酸性气道炎症。所有患者的中位FENO水平为18[12, 35]ppb,范围为5-300 ppb。慢性咳嗽伴过敏史患者的中位FENO水平高于无过敏史患者(Z=2.25,P=0.029)。FENO水平与诱导痰嗜酸粒细胞显著相关(r=0.281,P<0.001)。FENO诊断有过敏史患者和无过敏史患者嗜酸性气道炎症的AUC分别为0.677(95%CI,0.548-0.806)和0.708(95%CI,0.660-0.756)。有过敏史患者预测嗜酸性气道炎症的FENO临界值明显高于无过敏史患者(72 ppb vs 28.5 ppb)。结论 过敏史可减弱FENO对慢性咳嗽患者痰中嗜酸性气道炎症的预测作用,值得临床重视。

Objective To investigate the impact of a history of atopy on the value of fractional exhaled nitric oxide(FENO) for predicting sputum eosinophils in patients with chronic cough. Methods A total of 868 patients with persistent cough lasting more than 3 weeks without pulmonary infection were enrolled, including 119 patients with subacute cough(defined as cough lasting 3-8 weeks) and 749 with chronic cough(longer than 8 weeks). The predictive value of FENO level for sputum eosinophilia was analyzed using receiver-operating characteristic(ROC) curve analysis, and the area under the curve(AUC)was calculated. The atopy status of the patients was determined by screening for history of allergy, hay fever, or animal or food allergies. Results Of the 868 patients enrolled, 173 patients(19.9%) had eosinophilic airway inflammation(EAI). In the overall patients, the median(Q1, Q3) FENO level was 18(12, 35) ppb, ranging from 5 to 300 ppb. The patients with chronic cough and a positive history of atopy had a higher median FENO level than those without atopy(24 [13, 50] vs 18 [11, 34];Z=2.25, P=0.029), and FENO level was significantly correlated with EAI(r=0.281, P<0.001). The AUCs of FENO for diagnosis of airway eosinophilia in patients with atopy and those without atopy were 0.677(95% CI: 0.548-0.806) and 0.708(95% CI: 0.660-0.756),respectively. The optimal cut-off value of FENO for diagnosing EAI was higher in patients with atopy than in those without atopy(72 vs 28.5 ppb). Conclusion A history of atopy reduces the predictive value of FENO level for EAI in patients with chronic cough, suggesting the importance of examining the atopic status when interpreting test results of FENO.