2 | MATERIALS AND
METHODS
2.1 | Study sample
A cross-sectional survey was performed in Chengdu, Sichuan Province in
Southwest China. Four districts were chosen for participant recruitment,
including a country village, a town, a county seat, and a city. Two
kindergartens, two primary schools, and two junior middle schools from
each district were randomly chosen to participate and the questionnaire
was voluntarily completed by the children’s guardians. The sample was
children aged 2–14 years. Children with a history of neuromuscular
disease, craniofacial syndromes, cerebral palsy, sickle cell disease,
mucopolysaccharide storage disease, or immunodeficiency were excluded.
Participants were also excluded if they had mental or physical
impairment severe enough to cause abnormal behaviors, including
congenital disease, intellectual disability, or a psychiatric disorder.
The study was approved by the Biomedical Research Ethics Committee of
the West China Hospital of Sichuan University. Written informed consent
was obtained from each guardian before completing the questionnaire.
2.2 | Questionnaire
The investigators explained the purpose of the study and administered
informed consent before administering the questionnaire. The following
items from our parent-report questionnaire were used for analyses: (1)
demographic factors including age, sex, race, weight, height, and
district (city, suburb, county seat, town, or countryside village); (2)
socioeconomic factors including family income and parental education;
(3) delivery method (natural labor, Cesarean section), gestational age
(premature birth, full-term birth, post-term birth), parental age at
delivery, maternal pregnancy disease, and parental history of
obstructive sleep apnea hypopnea syndrome; (4) symptoms of upper
respiratory tract infection during the past six months, including
tonsillitis, chronic rhinosinusitis, AR, and asthma; (5) passive smoke
exposure (child exposed to secondhand smoke), maternal smoking and
secondhand smoke exposure during the child’s gestation; (6) and snoring;
based on the OSA-5 survey7, participants were divided
into three groups for comparisons (non-snorers = “never”, occasional
snorers = “rarely” or “sometimes”, and habitual snorers =
“frequently” or “all the time.”
2.3 | Data analysis
All analyses were performed using SPSS version 22.0. Data are presented
as mean ± SD, median (interquartile range), and percent, for parametric,
nonparametric, and categorical data, respectively. Parametric and
nonparametric variables were compared using one-way analysis of variance
and Mann–Whitney tests. Categorical variables were compared using χ2
tests. Multivariate logistic regression analyses were subsequently
performed to further confirm the association between potential risk
factors and HS. The association was assessed in logistic regression
models adjusted for age, sex, and BMI.