Is the atopy patch test with house dust mites specific for atopic dermatitis?

Area of Science:

• Allergen immunotherapy
• Dermatology
• Immunology

Background:

• The atopy patch test (APT) is used to diagnose atopic dermatitis (AD) by testing reactions to aeroallergens.
• Previous studies have reported positive APT results in individuals without AD, including atopic subjects without dermatitis and healthy individuals.

Purpose of the Study:

• To assess the response to the atopy patch test (APT) using house dust mites (HDM) in individuals without AD.
• To compare APT outcomes in non-AD subjects with those in AD patients.
• To evaluate differences between two HDM allergen extracts with varying purification and concentrations.

Main Methods:

• Forty-seven atopic subjects without eczema (AWE), 33 nonatopic (NA) subjects, and 77 adult AD patients were tested.
• Two HDM extracts were used: purified bodies at 20% and whole bodies at 30% (300 μg/g Der p 1).
• Reproducibility of the APT was assessed in AD patients, AWE subjects, and NA subjects.

Main Results:

• Positive APT responses were observed in 37.7% of AD patients, 10.6% of AWE subjects, and 12.1% of NA subjects with the 20% extract.
• With the 30% extract, positivity rates were 41.6% in AD, 19.1% in AWE, and 12.1% in NA subjects.
• The rates and intensity of positive responses were significantly higher in AD patients compared to non-AD subjects (p < 0.01).

Conclusions:

• The atopy patch test (APT) with house dust mites (HDM) can yield positive results in subjects without atopic dermatitis (AD).
• Despite positivity in non-AD individuals, the APT with HDM appears to be more specific for diagnosing AD.
• The reproducibility of the APT was found to be satisfactory across all tested groups.