验证 ATS 临床实践指南中 FeNO 在哮喘中的切点。

Validation of ATS clinical practice guideline cut-points for FeNO in asthma.

机构信息

Respiratory Research Unit, Department of Respiratory Medicine, Bispebjerg University Hospital, Copenhagen, Denmark.

出版信息

Respir Med. 2018 Nov;144:22-29. doi: 10.1016/j.rmed.2018.09.014. Epub 2018 Sep 22.

DOI:10.1016/j.rmed.2018.09.014

PMID:30366580

Abstract

BACKGROUND

The American Thoracic society (ATS) has suggested using fractional exhaled nitric oxide (FeNO) to monitor the level of eosinophilic (EOS) airway inflammation in asthma, but validation of the proposed cut-points is required in real-life populations.

OBJECTIVE

To validate FeNO cut-points suggested by ATS in relation to sputum EOS count in a real life population of asthma patients.

METHODS

All patients referred consecutively over a 12-months period for specialist assessment of asthma, were examined with FeNO and induced sputum, and re-examined 12 months later. The predicted values of a positive and a negative test (PPV and NPV) for a cut off ≥3% EOS in sputum were calculated. Change in FeNO was defined in accordance with ATS (>20% or 10 ppb if FeNO was <50 ppb).

RESULTS

144 adult asthma patients were examined (59% female). Low FeNO (<25 ppb) at baseline was found in 94 (65%), FeNO between 25 and 50 ppb in 34 (24%) subjects and high FeNO >50 ppb in 16 (11%) subjects. The PPV for FeNO >25 ppb and >50 ppb to predict EOS ≥3% was 45% and 77%, NPV was 88% and 83%. The sensitivity decreased from 70% to 37% at the >50 ppb cut-off. A significant reduction in FeNO was associated with a reduction in sputum EOS (p = 0.01).

CONCLUSION

The findings support the validity of the FeNO cut-points suggested by ATS to monitor eosinophilic airway inflammation in asthma. However, in this real-life population, a large proportion of patients had intermediate FeNO values, which may limit the clinical usefulness of the ATS FeNO cut-points.

摘要

背景

美国胸科学会（ATS）建议使用呼出气一氧化氮（FeNO）来监测哮喘患者气道嗜酸性粒细胞（EOS）炎症水平，但需要在真实人群中验证所提出的切点。

目的

在哮喘患者的真实人群中验证 ATS 提出的 FeNO 切点与痰 EOS 计数的相关性。

方法

连续 12 个月内因哮喘专科评估而就诊的所有患者均接受 FeNO 和诱导痰检查，并在 12 个月后复查。计算了痰中 EOS 计数≥3%时阳性和阴性试验的预测值（PPV 和 NPV）。根据 ATS 标准定义 FeNO 的变化（>20%或 10 ppb，若 FeNO<50 ppb）。

结果

共检查了 144 例成年哮喘患者（59%为女性）。基线时发现低 FeNO（<25 ppb）者 94 例（65%），FeNO 在 25 至 50 ppb 之间者 34 例（24%），FeNO>50 ppb 者 16 例（11%）。FeNO>25 ppb 和>50 ppb 预测 EOS≥3%的 PPV 分别为 45%和 77%，NPV 分别为 88%和 83%。在>50 ppb 切点时，灵敏度从 70%降至 37%。FeNO 显著降低与痰 EOS 减少相关（p=0.01）。