Reproducibility of atopy patch tests with food and inhalant allergens

Area of Science:

• Pediatric Allergy and Immunology
• Dermatology
• Clinical Diagnostics

Background:

• Atopy patch tests (APT) are increasingly used for diagnosing food allergies in children with atopic eczema/dermatitis syndrome.
• Reproducibility data for APT, particularly with fresh food allergens and inhalants, are limited.
• Understanding APT reproducibility is crucial for its reliable clinical application.

Purpose of the Study:

• To investigate the reproducibility of duplicate atopy patch tests (APT) using both fresh and standardized food allergens, as well as inhalant allergens.
• To assess the reliability of APT in a large, unselected pediatric population.

Main Methods:

• A study involving 277 Italian school children was conducted.
• Duplicate APT were performed on the back using fresh food allergens (cow's milk, hen's egg, tomato, wheat flour), standardized food allergens, and standardized inhalant allergens (Dermatophagoides pteronyssinus, mixed grasses).
• Reproducibility was assessed using Cohen's Kappa coefficient.

Main Results:

• Reproducibility for food allergens (fresh and standardized) varied significantly, with 25-75% of tests showing discordant results between sides (Cohen's K ranging from 0.38 to 0.81).
• APT with inhalant allergens demonstrated perfect reproducibility (Cohen's K = 1.00).
• Significant variability was observed in APT results for food allergens compared to inhalant allergens.

Conclusions:

• The reproducibility of atopy patch tests differs notably between food and inhalant allergens.
• Further controlled studies are needed to elucidate the technical and immunological factors influencing APT reproducibility for different allergen types.
• Clinical interpretation of APT results, especially for food allergies, requires careful consideration of potential variability.