How helpful is the radioallergosorbent test in the diagnosis of allergic disease?

We compared the results of clinical history, skin testing, and radioallergosorbent test (RAST) scores on 274 patients seen in an allergy clinic, using nine different allergens, namely ragweed, oak, Bermuda grass, redtop, Timothy, Alternaria, cat hair, house dust, and dust mite. More than 90% of patients who reported clinical allergy to pollens had a positive skin test to the respective allergen. Only two thirds of these patients also had a positive RAST, while only one patient in this group had a positive RAST and a negative skin test. Of the patients reporting allergy to cat hair, 60% had a positive RAST but only 46% had a positive skin test. For the case of dust allergy, there was poor agreement between test results and history, since more than half of the patients who reported symptoms from dust exposure had a negative RAST and negative skin test results.