2.1 | Study population and clinical data
We enrolled 150 infants and young children (88 boys, 62 girls) aged
under 2 years with AD visiting our hospital, Samsung Medical Center, who
were living in the Seoul Metropolitan Area of Korea. Locations of their
residences are shown in Figure 1. AD was diagnosed according to the
Hanifin and Rajka criteria.16 They were followed up
until they were 3 or 4 years old.
At enrollment, demographic data were obtained, including date of birth,
age of AD onset, and body mass index (BMI). AD severity was assessed
using the SCORing Atopic Dermatitis (SCORAD) index, developed by the
European Task Force Group on AD in 1993.17 Subjects
were classified into three groups, ‘mild (< 25)’, ‘moderate
(25−49)’, and ‘severe (≥ 50)’, according to SCORAD at enrollment. Levels
of total IgE and specific IgE against egg white, cow’s milk, soybean,
wheat and peanut in the peripheral blood were measured using ImmunoCAP
(ThermoFisher Scientific Inc., Waltham, MA, USA) and considered positive
when levels were 0.69 kU/L or above.
To evaluate the status of AD, AD children were brought to the hospital
at least once a year until the age of 3 years. AD remission was defined
as absence of AD symptoms in the past 6 months without needing medical
treatments including topical corticosteroid (TCS).
When they visited the hospital at age 3, skin prick tests were performed
to detect specific IgE against common inhalant allergens includingDermatophagoides pteronyssinus , D. farinae , tree pollen
mixture, grass pollen mixture, weed pollen mixture, and cat and dog
dander (Lofarma, Milan, Italy). Histamine was used as a positive
control, and normal saline was used as a negative control. A positive
response to allergens in the skin prick test was determined when wheal
size was ≥ 3 mm with adequate reactions to controls.
Written informed consent was obtained from the parent or guardian of
each participating child. Study protocols were reviewed and approved by
the Institutional Review Board (IRB) of Samsung Medical Center (IRB No.
2014-07-064).