Volume 8, Number 1, January 2016

2 http://e-aair. org tional Health Insurance Corporation in Korea has covered all parts of medical fees for the whole population as a compulsory social insurance system. The authors found that the prevalence of physician-diagnosed AD in children aged less than 18 years in 2008 was 6.9%, 13 a slight decrease from 7.2% in 2003. However, national statistics data still have a limitation in diagnostic accuracy due to inter-observer variability. In this issue of the AAIR journal, Lee et al. 14 report the prevalence of AD in Korean children using data from the Korean National Health and Nutrition Examination Survey. They analyzed 8,947 children aged 18 years or younger across the country and demonstrated that 13.5% of children had ever been diagnosed with AD by a physician. Importantly, the authors have provided another method to examine AD prevalence in a general population, although it should be noted that this is not the first nationwide, population-based study on AD prevalence. 10, 11, 13 In addition, the authors provided a lifetime prevalence of AD rather than point prevalence and were dependent on parental reports for the diagnosis of AD, showing that methodological limitations of the previous studies still remain. Determination of the true prevalence of AD is crucial to evaluate the current status and prepare an appropriate strategy for primary, secondary, and tertiary prevention of AD. However, we need to understand the limitations of epidemiologic studies and that the different methodologies used so far are complementary and do not replace one another. We also have to recognize the necessity of prevalence studies performed on a regular basis in order to cope with common pediatric diseases such as AD.