Variations in risk of asthma and seasonal allergies between early- and late-onset pediatric atopic dermatitis: A cohort study

BackgroundAtopic dermatitis is associated with other allergic conditions, but variations in this “atopic march” are poorly understood.ObjectiveTo determine the impact of the age of atopic dermatitis onset on the risk for asthma and seasonal allergies.MethodsA cohort study was performed using the Pediatric Eczema Elective Registry, which is an observational cohort of subjects with pediatric onset atopic dermatitis.ResultsIn total, 3966 children were included, and 73% reported atopic dermatitis onset before age 2 years. At baseline, subjects with atopic dermatitis onset at ages 3 to 7 or 8 to 17 years had significantly lower rates of seasonal allergies and asthma than those with onset before age 2. During follow-up, the adjusted relative risks for incident seasonal allergies were 0.82 (95% confidence interval, 0.72-0.91) and 0.64 (95% CI confidence interval, 0.47-0.83) in the 3- to 7- and 8- to 17-years-old at onset groups compared with the age 2 years or younger at onset group. The adjusted risk for incident asthma was not significantly different between the older onset groups and the earliest onset group.LimitationsMisclassification bias may arise from using self-reported onset age data.ConclusionsThe timing of atopic dermatitis onset may explain part of the variation in the atopic march. These findings may improve future risk stratification of patients for treatment.