feno

According to the FeNO value at the first visit, the subjects were divided into different high- and low-FeNO groups according to the ATS guidelines and the Chinese multicenter study recommendations.依据首次就诊时的呼出气一氧化氮（FeNO）检测值，参照美国胸科学会（ATS, American Thoracic Society）指南及中国多中心研究推荐标准，将研究对象划分为高FeNO组与低FeNO组。