Gao Jie, Zhang Min, Zhou Liqin, Yang Xing, Wu Haigui, Zhang Jianfang, Wu Feng
Department of Respiratory Medicine.
Internal Medicine-Cardiovascular Department, The Third People's Hospital, Guangzhou Medical College, Huizhou, People's Republic of China.
Int J Chron Obstruct Pulmon Dis. 2017 Apr 27;12:1287-1293. doi: 10.2147/COPD.S134998. eCollection 2017.
Measurements of eosinophils in induced sputum and fractional exhaled nitric oxide (FeNO) are noninvasive biomarkers for assessing airway inflammation phenotypes in chronic obstructive pulmonary disease (COPD). Nevertheless, the clinical application of the correlation between FeNO levels and sputum eosinophilia is controversial. The study aimed to investigate the correlation and predictive relationship between FeNO levels and sputum eosinophils in patients with COPD exacerbation. It also examined the relationship between FeNO levels and blood eosinophil percentage.
A total of 163 patients with COPD exacerbation were included in the cross-sectional study. All patients underwent the following on the same day: FeNO test, spirometry, bronchodilator reversibility test, induced sputum, and routine blood test. They were classified as eosinophilic group or noneosinophilic group based on sputum eosinophilic percentage (≥2.5%)/FeNO levels (≥32 parts per billion [ppb]).
FeNO levels and blood eosinophilic percentage were higher in patients with sputum eosinophilia (n=62) compared to those without (31.35 ppb versus 21.43 ppb, =0.015; 2.71% versus 0.98%, <0.0001, respectively). Sputum eosinophilic percentage was higher with raised FeNO (n=34) compared to those with FeNO <32 ppb (5.12% versus 3.12%, =0.007). Eosinophils in induced sputum correlated with both FeNO levels (ρ=0.221, =0.005) and blood eosinophilic percentage (ρ=0.399, <0.001). There was no relationship between FeNO and blood eosinophilic percentage. Blood eosinophilic percentage was predictive of sputum eosinophilia (95% confidence interval [CI] =0.65-0.81, <0.001) at a cutoff point of 0.65% (sensitivity =73%, specificity =61.3%). FeNO levels were predictive of sputum eosinophilia (95% CI =0.53-3,071, =0.012) at a cutoff point of 17.5 ppb (sensitivity =65.1%, specificity =56.4%).
The clinical relevance of this study provides evidence that inflammatory biomarkers, including sputum eosinophilic percentage, FeNO level, and blood eosinophilic percentage, can be used to positively diagnose eosinophilic COPD. The FeNO level and blood eosinophilic counts/percentage, which determine an optimal cutoff for sputum eosinophilia, need more studies.
诱导痰中嗜酸性粒细胞测量和呼出一氧化氮分数（FeNO）是评估慢性阻塞性肺疾病（COPD）气道炎症表型的非侵入性生物标志物。然而，FeNO水平与痰嗜酸性粒细胞增多之间相关性的临床应用存在争议。本研究旨在探讨COPD急性加重患者FeNO水平与痰嗜酸性粒细胞之间的相关性及预测关系。同时也研究了FeNO水平与血嗜酸性粒细胞百分比之间的关系。
163例COPD急性加重患者纳入横断面研究。所有患者在同一天接受以下检查：FeNO检测、肺功能测定、支气管扩张剂可逆性试验、诱导痰检查和血常规检查。根据痰嗜酸性粒细胞百分比（≥2.5%）/FeNO水平（≥32十亿分之一[ppb]）分为嗜酸性粒细胞组或非嗜酸性粒细胞组。
与无痰嗜酸性粒细胞增多的患者相比，痰嗜酸性粒细胞增多的患者（n = 62）FeNO水平和血嗜酸性粒细胞百分比更高（分别为31.35 ppb对21.43 ppb，P = 0.015；2.71%对0.98%，P < 0.0001）。FeNO升高（n = 34）的患者痰嗜酸性粒细胞百分比高于FeNO < 32 ppb的患者（5.12%对3.12%，P = 0.007）。诱导痰中的嗜酸性粒细胞与FeNO水平（ρ = 0.221，P = 0.005）和血嗜酸性粒细胞百分比（ρ = 0.399，P < 0.001）均相关。FeNO与血嗜酸性粒细胞百分比之间无相关性。血嗜酸性粒细胞百分比在截断点为0.65%时可预测痰嗜酸性粒细胞增多（95%置信区间[CI] = 0.65 - 0.81，P < 0.001）（敏感性 = 73%，特异性 = 61.3%）。FeNO水平在截断点为17.5 ppb时可预测痰嗜酸性粒细胞增多（95% CI = 0.53 - 3,071，P = 0.012）（敏感性 = 65.1%，特异性 = 56.4%）。
本研究的临床相关性提供了证据，表明包括痰嗜酸性粒细胞百分比、FeNO水平和血嗜酸性粒细胞百分比在内的炎症生物标志物可用于阳性诊断嗜酸性粒细胞性COPD。确定痰嗜酸性粒细胞增多最佳截断值的FeNO水平和血嗜酸性粒细胞计数/百分比需要更多研究。
