Research indicates that atopic dermatitis (AD) is associated with other allergic conditions, but variations in this “atopic march” are poorly understood, says Joy Wan, MD.

“The concept of the atopic march suggests that some patients with AD subsequently develop asthma and/or seasonal allergies,” says Dr. Wan. “However, not all individuals with AD complete this atopic march.”

To determine the impact of age of AD onset on the risk for asthma and seasonal allergies, Dr. Wan and colleagues conducted a study—published in the Journal of American Academy of Dermatology—using the Pediatric Eczema Elective Registry to analyze children who reported AD.

In total, 3,966 children were included, with 73% reporting AD onset before age 2 years. At baseline, subjects with AD onset at age 3 to 7 years 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 and 0.64 in the 3- to 7- and 8- to 17-years-old at onset groups when 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.

“Our findings suggest that early and late onset atopic dermatitis may differ in other meaningful ways that warrant further study,” says Dr. Wan. “Our findings may help improve risk stratification and prognostication of patients. Clinicians may consider counseling patients with earlier onset AD about their greater risk of seasonal allergies and asthma.”