The lifetime prevalence of wheezing fell from 19.3% in 1995 to 14.4% in 2000 in Korea, whereas the number of affected children increased during this period in other countries.4 In addition, the prevalence of wheezing in the previous 12 months decreased from 10.5% in 1995 to 5.2% in 2000 in Korea.4 In contrast to the increased prevalence of asthma in 13- to 14-year-old children in Japan, the prevalence decreased in Korea. This decrease was partially attributable to a greater awareness of symptoms, early diagnosis, and proper management of childhood asthma by caregivers and physicians, following a successful Nationwide Asthma Campaign. In this issue, Kwon et al.5 showed that there was little change in asthma prevalence between 2005 Lessons Learned from the Prevalence of Childhood Asthma in Korea Ha-Baik Lee Department of Pediatrics, Hanyang University College of Medicine, Seoul, Korea (13.0%) and 2008 (11.7%) based on the results of an epidemiological study conducted in metropolitan Seoul in 2008, using the same methodologies. A comparison of asthma prevalence among sequential phases of the ISAAC revealed similar trends. The rate for any diagnosis of asthma ever was 8.7% in 1995, 9.4% in 2000, 7.6% in 2005, and 7.9% in 2008. The prevalence of asthma treatments during the previous 12 months was 3.5% in 1995, 3.3% in 2000, 3.0% in 2005, and 2.7% in 2008.

Several risk factors are important in the development of asthma in children, and although some childhood asthmatics 'outgrow' the disease, asthma more commonly persists throughout adulthood. Both genetic susceptibility and environmental factors contribute to the development and persistence of asthma symptoms in children.6 Arruda et al.7 reported that risk factors for asthma include early sensitization to airborne allergens, a history of atopic dermatitis or allergic rhinitis, maternal smoking during pregnancy, passive smoking, lower respiratory infections, air pollution, and various genetic polymorphisms. The risk factors for asthma symptoms in Korean children are similar to those identified in Phase Three of the ISAAC; these include body mass index, passive smoking, and pets.8 In this paper, striking risk factors for asthma development were male gender; a history of atopic dermatitis, allergic rhinitis, or viral bronchiolitis; parental asthma; use of antibiotics during infancy; exposure to molds in the house during infancy; and moving to a new house, especially in genetically susceptible individuals.5 These results offer an opportunity to better understand asthma development.

In general, medical research has made progress in many human diseases, and advances in asthma research have reduced the toll of the disease. Nevertheless, much work remains. One common goal is to refocus attention on the prevalence and risk factors based on epidemiological studies of childhood asthma. However, efforts must still be directed toward better prevention and management of the disease, with a goal of minimizing the potential deterioration of lung function. It is important to educate the public and the medical community regarding more effective preventive measures and therapies for asthma.