Associations between metabolic syndrome and allergic diseases a nationwide study in Korea and literature review

Atopic dermatitis (AD), allergic rhinitis (AR), and asthma are typical allergic diseases, with a common pathogenesis involving increased type 2 immunity. Despite numerous studies, the association between these diseases and metabolic syndrome (MetS) remains controversial. This study aimed to explore relationships between AD, AR, and asthma both to MetS and to each of its components. Population-based, cross-sectional data were obtained from the Korean National Health and Nutrition Examination Survey from 2019 to 2020. Multiple logistic regression analyses were conducted to evaluate the association between allergic diseases and MetS. The results were compared with those of previous studies of the association between MetS and allergic diseases, identified in a literature review following a search of PubMed and the Cochrane Library. Based on assessments of 1,329, 4,824, and 1,172 patients with AD, AR, and asthma, respectively, negative associations between both AD and AR and MetS were determined, after adjusting for confounding factors. By contrast, asthma was positively associated with MetS (odds ratio [OR] 0.58, 95% confidence interval [CI] 0.50-0.67; OR 0.73, 95% CI 0.67-0.78; OR 1.70, 95% CI 1.51-1.92, respectively). The heterogeneous findings highlight the need for further investigation of associations between the studied allergic diseases and MetS as well as each of its components.