Association between obesity and atopic disorders in Chinese adults: an individually matched case–control study

BACKGROUND Obesity is regarded as a potential risk factor for atopy. The aim of this study was to assess the associations of obesity with atopic dermatitis, rhinitis, asthma and food allergy in Chinese adults. METHODS Two hundred and sixty six (266) atopic cases in Harbin, China, were identified according to the current Chinese guidelines for the diagnosis of atopic diseases. All cases had a previous diagnosis of atopic disorders (atopic dermatitis, rhinitis, asthma or food allergy) and were positive in one or more allergen specific IgE tests to 16 common allergens in the region. Each case was individually matched to two healthy controls based on their age, sex, and residential regions. All 532 healthy controls were negative in allergen specific IgE tests. The associations of obesity with four atopic disorders were assessed using a conditional logistic regression method. RESULTS Obesity was significantly associated with the presence of atopic diseases (OR = 3.2, 95% CI: 1.8, 5.7). Males and females had a similar association (OR = 3.1 for males and 3.2 for females). The associations of obesity with atopic dermatitis (OR = 2.7, 95% CI: 1.2, 6.3) and atopic rhinitis (OR = 3.1, 95% CI: 1.1, 8.7) were statistically significant. Although obesity was positively associated with atopic asthma, this association was not statistically significant (OR = 3.4, 95% CI: 0.6, 19.9). The association between obesity and food allergy was weak and not significant (OR = 1.1, 95% CI: 0.4, 3.7). CONCLUSIONS Obesity is positively associated with the presence of atopic diseases in Chinese adults. Specifically, obesity is significantly associated with atopic dermatitis and rhinitis. Our findings warrant further investigation on the causal nature between obesity and atopic diseases and the effect of weight reduction on preventing atopic diseases.