Division of Pulmonary and Critical Care, University of California, San Francisco-Fresno, 155 N Fresno St, Fresno, CA, 93701, USA.
Department of Internal Medicine, University of California, San Francisco-Fresno, 155 N Fresno St, Fresno, CA, 93701, USA.
Lung. 2018 Aug;196(4):455-462. doi: 10.1007/s00408-018-0132-8. Epub 2018 Jun 18.
Fraction of exhaled nitric oxide (FE) has been proposed as a non-invasive biomarker for allergic inflammation seen in asthma. Many asthmatics in clinical practice have never had spirometry and recent data report misdiagnoses in patients with physician diagnosed (PD) asthma. The aim of this study was to assess the ability of FE to discriminate between those with and without airflow obstruction (AO) among patients with PD-asthma.
Frequent exacerbators of PD-asthma (with 2 or more asthma exacerbations leading to emergency room visit or hospitalization within last 12 months) were enrolled. All patients underwent diagnostic evaluations including spirometry, FE testing and serum immunoglobulin (IgE) and eosinophils. Serial spirometry and methacholine challenge testing (MCT) were performed as indicated. AO was defined by a decreased FEV1/FVC ratio (< 70% and/or < LLN), or a positive MCT.
Of the 222 patients with PD-asthma, AO was found in 136 (vs. 86 without AO). 81.6% of patients with AO and 66.2% without AO completed FE testing. There was no significant difference in the mean FE levels among patients with or without AO (40.8 vs. 30.4 ppb, P = 0.10). Likewise, there was no difference in the serum IgE levels and serum eosinophils.
Our analyses suggest that FE levels do not help discriminate between those with and without AO in patients with PD-asthma. Patients who experience symptoms of asthma may have elevated FE levels above the suggested cut points of 20-25 ppb. Objective confirmation of AO should be considered in all patients with PD-asthma, irrespective of FE levels.
呼气一氧化氮（FE）分数已被提议作为哮喘中过敏炎症的非侵入性生物标志物。在临床实践中，许多哮喘患者从未进行过肺活量测定，最近的数据报告称，在医生诊断（PD）哮喘患者中存在误诊。本研究旨在评估 FE 在 PD 哮喘患者中区分有无气流阻塞（AO）的能力。
纳入 PD 哮喘的频繁加重者（在过去 12 个月内因 2 次或更多哮喘加重而导致急诊就诊或住院）。所有患者均接受诊断评估，包括肺活量测定、FE 检测以及血清免疫球蛋白（IgE）和嗜酸性粒细胞。根据需要进行了系列肺活量测定和乙酰甲胆碱激发试验（MCT）。AO 通过 FEV1/FVC 比值降低（<70%和/或<LLN）或 MCT 阳性来定义。
在 222 例 PD 哮喘患者中，发现 136 例（与 86 例无 AO 相比）存在 AO。81.6%的 AO 患者和 66.2%的无 AO 患者完成了 FE 检测。有或无 AO 的患者的 FE 水平平均值无显著差异（40.8 与 30.4 ppb，P=0.10）。同样，血清 IgE 水平和血清嗜酸性粒细胞也无差异。
我们的分析表明，FE 水平无助于区分 PD 哮喘患者有无 AO。经历哮喘症状的患者可能会出现高于 20-25 ppb 建议临界值的 FE 水平升高。无论 FE 水平如何，所有 PD 哮喘患者都应考虑进行 AO 的客观确认。
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