Introduction COPD is a heterogeneous disorder with varied phenotypes. We aimed to determine the prevalence of asthma history, peripheral eosinophilia and elevated FeNO levels along with the diagnostic utility of peripheral eosinophilia in identifying airway eosinophilic inflammation. Methods National Health and Nutrition Examination Survey data were analysed for the study period 2007–2010. Subjects aged ≥40 years with postbronchodilator FEV1/FVC ratio <0.70 were included. Receiver operator curve analysis was performed for sensitivity analysis. A p value of <0.001 is considered statistically significant. Results A total of 3 110 617 weighted COPD cases were identified; predominantly male (64.4%) and non-Hispanic whites (86.1%). Among our COPD subjects, 14.6% had a history of doctor diagnosed asthma, highest among females and other race Americans. The overall prevalence of peripheral eosinophilia is 36%, 38.3% among COPD subjects with asthma history, and 35.6% among COPD without asthma history. The overall prevalence of elevated FeNO ≥25 ppb is 14.3%; 28.7% among COPD subjects with asthma history and 13.0% among COPD without asthma history. Discussion The prevalence of FeNO levels ≥25 ppb and peripheral eosinophilia was significantly higher among COPD subjects with asthma compared with COPD without asthma history. Not all COPD subjects with peripheral eosinophilia and elevated FeNO levels have a reported history of asthma. Our study supports clinically phenotyping COPD subjects with eosinophilic inflammation be independent of their asthma history and peripheral eosinophilia can be used as a surrogate marker in resource-limited settings. All data relevant to the study are included in the article or uploaded as online supplemental information.

中文翻译：

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慢性阻塞性肺病中的嗜酸性粒细胞增多和呼出气一氧化氮分数水平

简介 COPD 是一种具有多种表型的异质性疾病。我们旨在确定哮喘病史、外周嗜酸性粒细胞增多和 FeNO 水平升高的患病率，以及外周嗜酸性粒细胞增多在识别气道嗜酸性粒细胞炎症中的诊断效用。方法对2007-2010年研究期间的全国健康与营养调查数据进行分析。包括年龄≥40 岁且支气管扩张剂后 FEV1/FVC 比率 <0.70 的受试者。接受者操作曲线分析用于敏感性分析。p 值 <0.001 被认为具有统计学意义。结果共识别出3 110 617例加权COPD病例；主要是男性（64.4%）和非西班牙裔白人（86.1%）。在我们的 COPD 受试者中，14.6% 有医生诊断为哮喘的病史，在女性和其他种族美国人中最高。外周嗜酸性粒细胞增多症的总体患病率为 36%，在有哮喘病史的 COPD 受试者中为 38.3%，在无哮喘病史的 COPD 受试者中为 35.6%。FeNO ≥25 ppb 升高的总体患病率为 14.3%；在有哮喘病史的 COPD 受试者中为 28.7%，在无哮喘病史的 COPD 受试者中为 13.0%。讨论 与无哮喘病史的 COPD 相比，患有哮喘的 COPD 受试者中 FeNO 水平≥25 ppb 和外周嗜酸性粒细胞增多的患病率显着更高。并非所有外周嗜酸性粒细胞增多和 FeNO 水平升高的 COPD 受试者都有哮喘病史。我们的研究支持对患有嗜酸性粒细胞炎症的慢性阻塞性肺病患者的临床表型进行独立于他们的哮喘病史，并且外周嗜酸性粒细胞增多可用作资源有限环境中的替代标志物。