Participant recruitment and characterization
AIRWEIGHS is a single-center, randomized, parallel-assignment,
quadruple-masked clinical trial of an air purifier intervention for
obesity-associated asthma (NCT02763917). The study was approved by the
IRB-1 Committee of the institutional review board of Johns Hopkins
University School of Medicine (IRB00074171). All participants gave
assent, and all primary caretakers gave written informed consent.
Participants were recruited from patients seen at the Johns Hopkins
outpatient clinics and the pediatric emergency department, community
engagement activities, recruitment flyers posted in public locations and
a registry of previous study participants. Eligible participants were
aged 8–17 years, nonsmokers, and had physician-diagnosed asthma by
National Asthma Education and Prevention Program (NAEPP) criteria with
at least one exacerbation in the prior year11. Those
who had other significant cardiopulmonary disease were excluded. A
diagram of the participant flow is shown in Figure 1 .
Sociodemographic information was obtained by participant or caregiver
report. Body weight and height were measured in triplicate and each
averaged, from which body mass index (BMI) was calculated and converted
to a normalized z-score based on the 2000 Centers for Disease Control
and Prevention (CDC) growth charts12,13.