The art and science of allergy skin testing

Demographic information, symptoms, and allergy skin test data from 809 patients from four allergy practices (A, B, C, and D) were statistically evaluated. A panel of 42 allergens were used for a total of 24,293 tests. Allergen positivity ranged from 51% for house dust to 9% for cat/dog. The patient population had primarily respiratory tract spring symptoms. Significant differences between the practices were found for (1) the number of skin tests done per patient, (2) the number of positive tests per patient, and (3) the grading of a positive test. A patient had a 3-fold to 6-fold greater chance of being found atopic by practice C or D than by practice A with practice B being intermediate. These differences highlight the need for less variation and better diagnostic standardization in the practice of allergy.