Methods: We conducted questionnaire survey using a Korean version of International Study of Asthma and Allergies in Childhood (ISAAC) questionnaire and anthropometric evaluation from October to November in 2012. AD was defined by existence of chronic eczema over 6 months based on the ISAAC questionnaire. SCORAD (SCORing Atopic Dermatitis) index were evaluated for 227 children with AD. Children were divided into 2 groups according to the SCORAD index : 1) mild-to-moderate AD (SCORAD index < 40); 2) severe AD (SCORAD index ≥ 40). Skin prick test to 18 allergens and blood test were completed for 188 children with AD.
Results: Among 2,109 children, 543 children (25.0%) were designated as having AD. One hundred and ninety children had mild-to-moderate AD (83.7%) and 37 children had severe AD (16.3%). Prevalence of obesity (BMI ≥ 95p) in AD group (n=38, 8.0%) was significantly higher than that of non-AD group (n=62, 4.5%). Proportion of children experienced breast milk feeding over 6 months in AD group (n=250, 46.7%) was significantly higher than that of non-AD group (n=635, 41.3%). There were no significant differences between AD group and non-AD group in terms of sex, age, BMI, history of breast milk feeding ever and mode of delivery. Geometric means (range of 1 SD) of blood eosinophil percentage (5.78% [3.35-10.00]) and serum eosinophil cationic protein concentration (48.98 µg/L [43.84-2,189.52]) in severe AD group were significantly higher than those of mild-to-moderate AD group (3.64% [1.67-7.96], 33.28 µg/L [12.02-92.20]). There were no significant differences between mild-to-moderate AD group and severe AD group in terms of age, BMI, birth weight, obesity, mode of delivery, history of breast milk feeding ever, serum hemoglobin and total IgE concentration. Risk factors for having AD were male sex (aOR 1.25 [1.01-1.55]), obesity (aOR 1.08 [1.17-2.76]) and history of breast milk feeding over 6 months (aOR 1.25 [1.01-1.55]). Atopy in skin prick test to 18 allergens was observed in 70% of AD group children. Majority (57.8%) of children were reactive to house dust mites, followed by pollen (29.9%), animal dander (26.2%), mold (18.7%) and food allergen (9.1%).
Conclusions: Prevalence of AD is 25.9% in the Gyeonggi-do, South Korea and it is similar to the prevalence of recent Korean nation-wide study in 2010 (27.0%). Male sex, obesity and history of breast milk feeding over 6 months independently increase risk of having AD.