Study population
The COhort for Childhood Origin of Asthma and Allergic diseases (COCOA)
is a prospective, general population-based birth cohort study designed
to investigate the individual and interactive effects of genetics,
perinatal environment, maternal lifestyle, and psychosocial stress of
mother and child on pediatric susceptibility to allergic
diseases.17 Regular follow-up visits involving
physician examination and self-report questionnaires concerning the
environment were conducted at at least 26 weeks gestation, at birth,
6 months, 1 year, and then annually.18 From yearly
follow-ups of pediatric allergists, we collected information on the
allergic symptoms, diagnosis, and prescribed treatment. Among the 3,102
pairs enrolled in the COCOA cohort, 1,636 children were aged over 6
years. The 706 patients lacking clinical and laboratory data were
excluded, leaving 930 patients to be analyzed (Figure E1). The average
age of the patients was 8.02 years, and 52.7% were male. Significant
differences in birth weight, breastfeeding rates, and antibiotic use
before 1 year of age were observed between the included and excluded
groups (Table E1).
Allergic diseases including PFAS were diagnosed by a physician or
typical symptoms (itching, sore throat, or swelling) in the lips, mouth,
and throat immediately after eating fresh fruits or vegetables by
parental questionnaire. If PFAS was suspected, the trigger of PFAS was
also investigated.
The study was approved by the Institutional Review Boards of Asan
Medical Center (IRB No. 2008–0616), Samsung Medical Center (IRB No.
2009-02-021), Severance Medical Center (IRB No. 4-2008–0588), CHA
Gangnam Medical Center (IRB No. 2010–010), and Seoul National
University Hospital (IRB No. H-1401-086-550) before initiation. Written
informed consent was obtained from each patient’s parents or guardians
before the interview, confirmed by each IRB.