The Role of Skin Patch Test in Identifying Food Allergen-Induced Delayed Hypersensitivity Reactions in Children With Atopic Dermatitis

Abstract

Introduction Atopic dermatitis is a chronic, recurrent inflammatory skin condition [1]. The patch test is the gold standard used to identify type IV hypersensitivity reactions, with sensitivity and specificity ranging from 70% to 80% that can help identify food allergies in children with atopic dermatitis who do not have elevated serum IgE levels [2, 3]. Aim To use skin patch test as a way to determine which food products are most commonly associated with delayed allergic reactions, evaluate the relationship between these reactions and the child's age and assess the frequency of delayed allergic reactions in children with atopic dermatitis. Methods From 2022 to 2024, a diagnostic trial using the atopy patch test was conducted at the LUHS Kaunas Clinics, Pediatric Diseases Clinic, for children who were consulted by a pediatric allergist at the LUHS Children's Outpatient Clinic due to atopic dermatitis. The study included 299 children aged 3 months to 16 years. All children underwent a patch test with 25 food allergens: 14 standard and 11 self-provided. The results were evaluated after 48 and 72 hours. Data analysis was performed using the software IBM SPSS Statistics (29.0). The study results are presented as numerical data and percentages. The relationship between nominal variables was determined using the Chi-square test. Relationships between variables were considered statistically significant if p < 0.05. The relationship between continuous variables was assessed using the Student‘s t-test. Differences between groups were considered statistically significant if p < 0.05. Results The five most frequently reactive food items overall (from 14 standard and 11 self-provided products) were: wheat (28.8%), buckwheat (26.4%), peanuts (25.4%), chicken (13.4%), and carrots (12.7%). Delayed reactions identified through patch testing were observed in 44 cases (14.7%). Almost all children with atopic dermatitis and positive skin patch test were under 4 years old, comprising 43 children (97,7%). Children with positive skin patch test result were significantly younger (21,4 months) than those with negative results (31,6 months) (t(144.4) = 3.79, p < 0.001), with a mean difference of 10,2 months (95% CI: 4.89 - 15.53). Conclusions Delayed allergic reactions can be diagnosed using skin patch test for children with atopic dermatitis. The most frequently identified food allergens for children were wheat, buckwheat, peanuts, chicken and carrots. Patch test results were more frequently positive in children under 4 years old, suggesting that patch testing is more informative when conducted in younger children.