Kumar Raj, Gupta Nitesh
Vallbhbhai Patel Chest Institute, University of Delhi, 110007, New Delhi, India.
Adv Respir Med. 2017;85(4):186-192. doi: 10.5603/ARM.2017.0031.
Asthma is a chronic airway inflammatory disorder. Nitric oxide (NO) is non-invasively measured in exhaled breath (FeNO). The aim of the study was to investigate the anthropometric and physiologic factors that influence FeNO measurements. Also, to evaluate FeNO correlation with spirometry and inflammatory markers in asthma and rhinitis.
The study was a prospective analysis of asthma (BA) and rhinitis (AR) in patients enrolled from outpatient clinics between 2011 and 2015. Healthy controls (HC) were enrolled from the community. All subjects underwent baseline spirometry with reversibility, FeNO measurements, skin prick tests, and blood sampling for absolute eosinophil counts and serum total IgE levels.
Of 528 enrolled participants, 215 were BA, 248 were BA-AR and 65 were HC. The mean FeNO was higher in atopic versus nonatopic subjects (34.14 vs. 25.99; p < 0.001); asthmatics versus non-asthmatics (30.46 vs. 12.91; p < 0.001), and in participants with BA-AR, compared to those without BA-AR (32.56 vs. 30.46; p < 0.001). The odds ratio for FeNO in the study population showed a significant positive association with male gender, absolute eosinophil count (AEC), breathlessness, duration of symptoms, family history and atopy. In examining the diagnostic accuracy of FeNO for asthma, the AUC for FeNO value is 0.833 (95% confidence interval [CI], 0.717-0.901), with cut-off levels to screen for asthma being 19.45 at 71.2% sensitivity and 81.8% specificity (p < 0.001). The Positive Predictive Value 96.84% (95% CI: 94.43-98.23) and Negative Predictive Value 30% (95% CI: 23.78-37.05) for asthma prediction with FeNO.
The study highlights the importance of estimation of anthropometric parameters and dyspnea assessment in the evaluation of FeNO levels. Also, the presence of atopy may influence the results in the interpretation of FeNO readings. Moreover, the study have demonstrated that spirometry and FeNO have no significant correlation, which further lays emphasis on them as being different physiological parameters of asthma.  .
哮喘是一种慢性气道炎症性疾病。可通过呼出气体无创测量一氧化氮（NO）（呼出一氧化氮，FeNO）。本研究的目的是调查影响FeNO测量的人体测量学和生理学因素。此外，评估哮喘和鼻炎患者中FeNO与肺功能测定及炎症标志物的相关性。
本研究是对2011年至2015年从门诊招募的哮喘（BA）和鼻炎（AR）患者进行的前瞻性分析。健康对照（HC）从社区招募。所有受试者均接受了具有可逆性的基线肺功能测定、FeNO测量、皮肤点刺试验以及用于绝对嗜酸性粒细胞计数和血清总IgE水平的血液采样。
在528名登记参与者中，215名是BA患者，248名是BA-AR患者，65名是HC。特应性受试者的平均FeNO高于非特应性受试者（34.14对25.99；p<0.001）；哮喘患者高于非哮喘患者（30.46对12.91；p<0.001）；与无BA-AR的参与者相比，BA-AR参与者的平均FeNO更高（32.56对30.46；p<0.001）。研究人群中FeNO的优势比显示与男性、绝对嗜酸性粒细胞计数（AEC）、呼吸困难、症状持续时间、家族史和特应性呈显著正相关。在检查FeNO对哮喘的诊断准确性时，FeNO值的曲线下面积（AUC）为0.833（95%置信区间[CI]，0.717-0.901），筛查哮喘时的截断水平为19.45，敏感性为71.2%，特异性为81.8%（p<0.001）。FeNO预测哮喘的阳性预测值为96.84%（95%CI：94.43-98.23），阴性预测值为30%（95%CI：23.78-37.05）。
该研究强调了在评估FeNO水平时人体测量参数估计和呼吸困难评估的重要性。此外，特应性的存在可能会影响FeNO读数的解读结果。而且，该研究表明肺功能测定和FeNO之间无显著相关性，这进一步强调了它们是哮喘不同的生理参数。
