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Is the prevalence of atopic dermatitis in Korean children decreasing? : National Database 2009-2014.

BACKGROUND
The prevalence of atopic dermatitis (AD) in children is increasing in many developing countries.


OBJECTIVE
This study aimed to explore trends in the prevalence of AD in Korean children.


METHODS
We analyzed data from the Korean National Health Insurance Service (NHIS) from 2009 to 2014. Data for the estimated populations were collected from the Statistics Korea. The annual prevalence of AD was obtained by dividing the number of patients by the estimated population each year. We analyzed the prevalence of AD in 2014 and evaluated the change in the annual prevalence of AD from 2009 through 2014.


RESULTS
The estimated population of children aged 18 years or younger was 9,992,581 in 2014, and the number of children with AD was 578,678 with the prevalence of 5.8%. The prevalence was 17.2% in infants aged 12-23 months, which decreased substantially to 7.3%, 3.2% and 2.4% at 5, 12 and 18 years of age, respectively. In the pediatric age group, the prevalence of AD slightly decreased from 6.5% to 5.8% from 2009 through 2014. Notably, in infants aged less than 24 months, the prevalence decreased from 20.8% to 15.4%.


CONCLUSIONS
Based on the Korean NHIS database, the prevalence of AD in Korean children aged 18 years or younger appears to be decreasing, especially in infants. Although the reason is not clear, an increase in breast milk feeding, vaginal delivery or consumption of probiotics might be involved. Further studies are needed to confirm this trend and to explain the possible mechanisms.