Associations between sensitisation to allergens and allergic diseases: a hospital-based case–control study in China

OBJECTIVES: To assess the associations of sensitisation to common allergens with atopic dermatitis, allergic rhinitis and allergic asthma in adults. DESIGN: Case–control study. SETTING: Data were collected from the First Affiliated Hospital of Harbin Medical University in Harbin, China. PARTICIPANTS: Cases were 5111 patients with physician-diagnosed atopic dermatitis (n=2631), allergic asthma (n=1320) and allergic rhinitis (n=1160) recruited from the department of allergy from March 2009 to December 2017. Controls were 2576 healthy adults who underwent physical examination at the same hospital during the same period. MAIN OUTCOME MEASURES: Specific IgE levels to 16 common food, indoor and outdoor allergens were assessed in all participants. Adjusted ORs and 95% CIs for the association between allergen sensitisation and allergic diseases were estimated using multivariate logistic regression. RESULTS: The prevalence of allergen sensitisation was higher in patients with atopic dermatitis (indoor=17.14%, outdoor=12.85%, food=21.44%), allergic rhinitis (indoor=23.18%, outdoor=26.81%, food=8.94%) and allergic asthma (indoor=24.65%, outdoor=16.46%, food=14.31%) compared with controls (indoor=11.03%, outdoor=6.84%, food=5.83%). After adjustment for potential confounding variables, there was a dose–response relevance between the levels of allergen-specific IgE and allergic diseases (p trend <0.0001). The number of allergens to which a patient was sensitised increased the risk of allergic diseases (atopic dermatitis: highest adjusted OR=4.28, 95% CI 2.57 to 7.11; allergic rhinitis: highest adjusted OR=13.00, 95% CI 3.76 to 45.00; allergic asthma: OR=2.37, 95% CI 1.67 to 3.37). CONCLUSION: There was a dose–response relevance between levels of allergen-specific IgE and allergic diseases’ prevalence, and multiple sensitisations increased the risk of allergic diseases. This study provides evidence for the prophylaxis of allergic diseases.