Methods
The study sample included 60 children with treatment-refractory
wheeze/asthma referred to a university-based specialty clinic serving a
mixed urban-rural population in central Virginia. Enrollees underwent a
HHe-3 lung MRI within eight weeks of characterization procedures adapted
from the NIH/NHLBI Severe Asthma Research Program 16.
Participants were treated according to GINA guidelines17 by an asthma specialist for a minimum of three
months before severity assignment 18. Details
regarding recruiting procedures and characterization16, treatment 17,19, and indications
for bronchoscopy 19 have been published previously.
Inclusion criteria included ages 3-17 years, diagnosis of problematic
wheeze (n = 11) or confirmed asthma (n= 49) based on change in
FEV1% ≥ 12% from baseline post-bronchodilator (BD),
and/or a previous positive methacholine bronchoprovocation test, and
treatment for a minimum of three months with ≥1 asthma controllers.
Inadequate control was defined according to an asthma control test
(ACT/cACT) <20, 2 or more exacerbations in the year prior to
enrollment, and/or persistent airflow limitation
(FEV1/FVC < 90th %
predicted) 20. Exclusion criteria included premature
birth < 36 weeks gestation, inability to cooperate with the
MRI procedures, and significant non-asthmatic diagnoses including
cardiac disease, cystic fibrosis, and a documented lower respiratory
infection within six weeks of the enrollment visit. Study participation
required informed consent and protocols were approved by the University
of Virginia Institutional Revew Board (IRB# 157200 and #18422). The
study was listed on ClinicalTrials.gov (NCT02577497).