Date Published: December 27, 2018
Publisher: BioMed Central
Author(s): Jianghong Wei, Libing Ma, Jiying Wang, Qing Xu, Meixi Chen, Ming Jiang, Miao Luo, Jingjie Wu, Weiwei She, Shuyuan Chu, Biwen Mo.
High bronchodilator reversibility in adult asthma is associated with distinct clinical characteristics. In this study, we aim to make a comparison with T-helper 2 (Th2)-related biomarkers, lung function and asthma control between asthmatic patients with high airway reversibility (HR) and low airway reversibility (LR).
Patients with asthma diagnosed by pulmonologist according to Global Initiative for Asthma guidelines were recruited from the outpatient department of our hospital from August 2014 to July 2017. Patients were divided into HR and LR subgroups based on their response to bronchodilators of lung function (HR = Δforced expiratory volume in one second (FEV1) postbronchodilator ≥ 20%). Blood eosinophil count and serum IgE level, which are biomarkers of T-helper (Th)-2 phenotypes, were detected for patients. Asthma Control Test (ACT) was used to assess asthma control after the first-month initial treatment.
A total of 265 patients with asthma were followed 1 month after initial treatment. HR group shows a higher level of Th2-high biomarkers (blood eosinophil count (10^9/L): 0.49 ± 0.28 vs 0.36 ± 0.19, P < 0.01; IgE (ng/ml): 1306 ± 842 vs 413 ± 261, P < 0.01), lower baseline lung function (FEV1%pred: 51.91 ± 19.34% vs 60.42 ± 19.22%, P < 0.01; forced expiratory flow (FEF)25–75: 0.76 ± 0.37 vs 1.00 ± 0.67, P < 0.01; FEF25–75%pred: 21.15 ± 10.09% vs 29.06 ± 16.50%, P < 0.01), and better asthma control (ACT score: 22 ± 4 vs 20 ± 4, P = 0.01) than LR group. HR was associated with a decreased risk of uncontrolled asthma after the first-month initial treatment (adjusted OR: 0.12 [95% confidence intervals: 0.03–0.50]). HR is a physiologic indicator of lower lung function and severer small airway obstruction, and is more related with an increased level of Th2-biomarkers than LR. Moreover, HR may indicate controlled asthma after the first-month initial treatment. This finding may contribute to identification of asthma endotype.
Airway bronchodilator reversibility is the characteristic that differentiates asthma population from patients with irreversible obstructive lung diseases . It has been emerged as a characteristic to categorize asthma patients into different phenotype , and a physiologic biomarker associated with co-morbidities of asthma patients . Interestingly, the high airway bronchodilator reversibility was found as a physiologic indicator for reduced lung function, and was associated with elevated Th2-biomarkers . Thus, airway bronchodilator reversibility may be a crosslinking point in understanding the diversity of asthma endotype, and then identify profiles to guide treatment . However, that previous study didn’t investigate obstruction in small airway, or asthma control after the initial treatment according to the Global Initiative for Asthma guidelines (GINA) alone . Therefore, we conducted this hospital-based cohort study to investigate immune pathway biomarkers, obstruction in small airway, and disease control after the initial treatment in asthma patients with high or low airway reversibility.
From August 2014 to July 2017, adult patients with asthma diagnosed by pulmonologists at the first time according to the definition of GINA  were recruited in the study from the Affiliated Hospital of Guilin Medical University, Guilin, China. Blood eosinophil count and serum IgE level were tested. Asthma control was assessed in terms of Asthma Control Test (ACT) after the first-month initial treatment with a face-to-face interview by pulmonologists [6, 7]. The study protocol was approved by the Institutional Review Board at the Affiliated Hospital of Guilin Medical University, and conformed to the declaration of Helsinki. Written informed consent was obtained from each subject.
Figure 1 shows the subject selection process. We excluded subjects if they had no record of lung function responding to bronchodilators, blood eosinophil count, serum IgE level, or ACT score. A total of 265 subjects were selected for final analyses.Fig. 1Selection of the study population
In our study, HR was more frequently associated with a higher level of Th2-biomarkers, lower lung function in baseline, and better asthma control after the first-month initial treatment than LR. Furthermore, HR and high FEF25–75 after inhaling short-acting bronchodilator were respectively associated with better asthma control. It may contribute to identifying the endotype of asthma by further clarifying the relationship between airway bronchodilator reversibility, obstruction in small airway, Th2-biomarkers and disease control after initial treatment.
In conclusion, HR is a physiologic indicator of lower lung function, particularly small airway obstruction, and is more related with an increased level of Th2-biomarkers than LR. Moreover, HR indicates well asthma control after the first-month initial treatment. Those findings may be help to identify the endotype of asthma.