Subjects and data collection
The study was approved by No. 20180308 of the Xiangya Hospital Ethics
Review Committee. From October 2018 to January 2019, 51 HCs and 55
asthma patients were chosen from the Respiratory Department and Physical
Examination Center of Xiangya Hospital, China. FEV1/FVC
ratio <0.7 and FEV1% <70% was
defined as the presence of asthma. The inclusive standards for the
patient group were between the age of 40 and 70 with a clear diagnosis
of asthma (according to the criteria of 2018 Global Strategy for Asthma
Management and Prevention) but without other respiratory
orĀ otherĀ diseases [19]. The HCs had no differences in age and gender
without asthma or other organic mental diseases, including smoking and
non-smoking controls. Quality control methods were strictly enforced.
After obtaining the written informed consent from each subject, we
collected questionnaire information (general condition, smoking history
and other respiratory diseases), pulmonary function testing and
peripheral blood samples. For our analysis, pulmonary function
parameters were adopted including forced expiratory volume in one second
as percentage of predicted volume (FEV1%), the
spirometric values of forced expiratory volume in one second
(FEV1), forced vital capacity (FVC), peak expiratory
force (PEF) and forced expiratory flow (FEF). Certified staff performed
all interviews and examinations. Moreover, feedback on work quality
would be regularly provided to field staff during the data collection
process, and secondary training would be conducted when necessary.