Airway structural abnormalities were more prominent in patients
with greater asthma severity
In Study 1, the Ai/BSA and Aw% from the 3rd to
9th generation of bronchi did not differ significantly
from those in the RB8 to RB9 segment (all P >0.05,Table E3 ). In medium-sized airways (the
3rd-6th generation), both patients
with moderate and severe asthma had significantly lower Ai/BSA than
control subjects and patients with mild asthma (bothP <0.05, Figure 1 ); however, the Ai/BSA in
control subjects and patients with mild asthma were comparable (bothP >0.05). Compared with those with moderate asthma,
patients with severe asthma yielded markedly smaller caliber from the
5th to 6th generation of bronchi
(P =0.018). Furthermore, significantly greater Aw% from the
3rd to 6th generation of bronchi was
seen in both patients with moderate and severe asthma than in control
subjects and patients with mild asthma (all P <0.05).
Severe asthma was associated with greater Aw% from the
5th to 6th generation of bronchi
compared with moderate asthma (all P <0.001). Aw% from
the 3rd to 6th generation of bronchi
was notably greater in patients with mild asthma than in control
subjects (P <0.05).
In small airways (the 7th-9thgeneration), both patients with moderate and severe asthma presented
with significantly smaller Ai/BSA and greater Aw% compared with
patients with mild asthma and control subjects (allP <0.05, Figure 1 ). Severe asthma yielded
markedly lower Ai/BSA and greater Aw% from the 7th to
9th generation of bronchi compared with moderate
asthma (all P <0.05). Despite comparable Ai/BSA,
patients with mild asthma yielded greater Aw% from the
7th to 9th generation compared with
control subjects. Collectively, patients with mild asthma had developed
airway remodeling (wall thickening) from the 3rd to
9th generation, even in the absence of airway luminal
narrowing. More prominent structural abnormalities were associated with
greater asthma severity, as evidenced by decreased airway caliber and
greater wall thickness (Figure 2 ). The airway inner area of
medium-sized airways (Ai/BSA3-6) correlated negatively, and the airway
wall area of medium-sized airways (Aw%3-6) correlated positively with
the duration of asthmatic symptoms (r=-0.306, P =0.002; r=0.282,P =0.004, respectively). However, the sputum eosinophil count did
not correlate with EB-OCT parameters (all P >0.05,Table E4 and Table E5 ).