Supplementary Material for: Prevalence of Atopy and Allergic Diseases in Korean Children: Associations with a Farming Environment and Rural Lifestyle

<i>Background:</i> The results of recent studies suggest that factors in rural environments may protect against the development of allergic diseases, but the underlying mechanisms are not well understood. The aim of this study was to investigate the prevalence of allergic diseases, to establish if this prevalence is influenced by migration from rural to urban areas and to identify environmental risk factors associated with these diseases. <i>Methods:</i> A cross-sectional study of children aged 9–12 years from a rural village, a rural town and an urban city in Korea was conducted. Demographic and disease-related information was obtained via a detailed questionnaire, and skin prick tests were performed. <i>Results:</i> There were significant differences in lifestyle and environmental factors between children from the rural village, the rural town and the urban children. The prevalence of allergic diseases and atopy was higher in urban children. A lower prevalence of allergic diseases and atopy was associated with farming parents, contact with farm animals during pregnancy, owning pets or a stable, breast-feeding and having older siblings. A comparison of rural village and rural town children revealed no evidence of an association of allergic diseases and atopy with farming parents, contact with farm animals during pregnancy or owning a stable. On the other hand, having older siblings and antibiotic use during infancy were significantly associated with allergic diseases and atopy in these children. <i>Conclusions:</i> Protective factors associated with a farming environment and/or rural lifestyle may influence the prevalence of allergic diseases and atopy in Korean children.

背景：近期研究结果提示，农村环境中的相关因素可能对过敏性疾病的发生具有保护作用，但其潜在机制尚未完全阐明。本研究旨在调查过敏性疾病的患病率，明确该患病率是否受农村向城市迁移的影响，并识别与这类疾病相关的环境危险因素。
方法：针对韩国某乡村、集镇及城市的9~12岁儿童开展横断面研究（cross-sectional study）。通过详细问卷收集人口统计学与疾病相关信息，并实施皮肤点刺试验（skin prick tests）。
结果：乡村、集镇及城市儿童在生活方式与环境因素方面存在显著差异。城市儿童的过敏性疾病及特应症（atopy）患病率更高。父母从事农业、孕期接触农场动物、饲养宠物或厩舍、母乳喂养以及拥有年长同胞，与较低的过敏性疾病和特应症患病率相关。对比乡村与集镇儿童的分析显示，未发现过敏性疾病及特应症与父母务农、孕期接触农场动物或饲养厩舍存在关联。而在该群体中，拥有年长同胞以及婴儿期使用抗生素，与过敏性疾病和特应症显著相关。
结论：与农业环境及/或农村生活方式相关的保护因素，可能影响韩国儿童过敏性疾病及特应症的患病率。