Methods: We performed a retrospective analysis of our entire primary care network of 1,050,094 children. We identified two cohorts: (1) a closed birth cohort of 29,661 children and (2) a cross-sectional cohort of 333,201 children. We utilized frontline healthcare provider-based diagnosis codes to determine the age of diagnosis, incidence, and prevalence of eczema, RAD, rhinitis, and allergies to specific foods.
Results: The peak age of diagnosis for eczema was < 0.5 years (11.1%), RAD was at age 1 year (8.9%), rhinitis was at age 2-3 years (2.4%), and food allergy was at age 1 year (1.9%). Eczema and rhinitis prevalence were 8.3% and 20.2%, respectively. RAD prevalence was 22.3%, a rate higher than previously reported and confirmed by sub-analysis of asthma-medication prescription data. Prevalence of food allergy was 7.2%. The most common allergenic foods were peanut (2.7%), milk (2.3%), egg (1.9%), shellfish (1.7%), and soy (0.8%) and food allergy predisposed to the development of RAD or rhinitis.
Conclusions: Compared to previous reports, we measured lower rates of eczema, and higher rates of RAD and asthma in our population. The distribution of the major food allergens diverged from prior figures, and food allergy was found to predispose to the development of RAD or rhinitis.