Long-Term Risk of Allergic Contact Dermatitis in Children With Atopic Respiratory Disease When They Reach Adulthood

Background: The long-term risk of allergic contact dermatitis (ACD) in children with atopic disease is a matter of debate. Objectives: The study aimed to assess the long-term risk of patients with childhood-onset atopic asthma and/or rhinitis (AtRD), with and without childhood-onset atopic dermatitis (CoAD), to develop ACD in adulthood. Methods: A prospective cohort study with 15-year follow-up was conducted on 620 consecutive young adult patients (age 18–25 years) with childhood-onset AtRD (before the age of 16), and 173 healthy control subjects. All participants underwent skin prick tests for inhalant and food allergens. Patients were assigned to 2 cohorts. The NAD cohort included 483 patients with AtRD who had never had signs of atopic dermatitis. The AD cohort included 137 patients who, in addition to AtRD, had a presence or previous history of CoAD (onset within the first 5 years of life). Patients who showed clinical suspicion of contact dermatitis during follow up performed a patch test with a panel of 40 contact allergens. Those who tested positive for at least one contact allergen were considered to have contact allergy (CA). Patients with CA in whom the positive patch test had clinical relevance, assessed through detailed exposure analysis, were considered to be suffering from ACD. Results: At the end of follow-up, the proportions of patients with CA (77.4% [106 of 137 patients] vs. 20.7% [100 of 483 patients]; p < 0.001) and patients suffering from ACD (52.6% [72 of 137 patients] vs. 14.7% [71 of 483 patients]; p < 0.001) were higher in the AD cohort than in the NAD cohort. In both cohorts, CA and ACD rates were higher than in control subjects (5.2% [9 of 173] controls; p < 0.001 and 1.7% [3 of 173 controls]; p < 0.001). In the overall group of participants, the multivariate Cox proportional hazards regression model showed that ACD was positively associated with AtRD (hazard ratio 1.67, 95% CI, 1.21–2.28, p = 0.001) and CoAD (hazard ratio 7.40, 95% CI, 5.74–9.52, p < 0.001) but not with IgE-mediated food allergy. In the AD cohort, the proportion of ACD did not differ between patients who had healed AD and those whose disease persisted into adulthood (49.2% [32 of 65 patients] vs. 55.5% [40 of 72 patients]), and the relative risk of ACD did not differ significantly between the two groups. Conclusions: Patients with childhood atopic asthma and/or rhinitis are exposed to an increased risk of ACD up to the fourth decade of life. The risk is independent of CoAD, even though the presence or past history of CoAD further increases the occurrence of ACD, regardless of whether patients have healed CoAD or not.