Comparison of intradermal skin test and multiple allergen simultaneous test results in canine atopic dermatitis

Intradermal skin test (IDST) is generally considered a useful tool in iden-tifying causal allergens in canine atopic dermatitis. Currently, multiple allergen simultaneous test (MAST), an in vitro testing method for allergen-specific immuno-globulin E, is being used as an alternative method. However, there are no reports comparing the IDST and MAST results in the same dogs. This study compared the results of both tests to evaluate the agreement and correlation between them. The sensitivity, specificity, and accuracy of the MAST were 76.2%, 64%, and 66.7%, respectively. Moderate positive predicted value (PPV, 50-75%) or high sensitivity (80-100%) were identified for indoor allergens, such as cat epithelia, house dust, and house dust mites. In contrast, high negative predicted value (NPV, 93.3-100%) and specificity (60-100%) were observed for environmental allergens and fungi. Although the agreement between IDST and MAST for all allergens was fair (κ = 0.301), that for each allergen was poor (κ < 0.01), except for birch (κ = 0.158). Spearman’s rank correlation analysis revealed a low correlation between the MAST and IDST results (ρ = 0.308, p = 0.001). As compared to the IDST results, the MAST results did not identify the causative allergens sufficiently. IDST may not be performed for environmental allergens and fungi with high NPV and specificity if the MAST result is negative, but it may have to be performed for indoor allergens with moderate PPV and high sensitivity when the MAST result is positive.