Skin testing compared with in vitro testing for screening allergic patients

A new FDA-cleared product has been introduced for screening suspected allergic patients using a small blood sample. The QUIDEL Allergen Screens (AS) are simple to use dipstick tests that measure allergen-specific IgE to ten of the most important regional allergens. We compared the results obtained by prick-puncture skin testing (ST) to those obtained with the AS on 103 patients with allergic symptoms. Of the 103 patients studied, there were 67 with positive skin tests, and 57 of those were positive by AS and ten were AS negative. Of the 36 with negative skin tests, 2 were positive by AS and 34 were AS negative. Compared with ST, the AS results gave a sensitivity of 85% and a specificity of 94% for identifying the allergic patient. Of the ten patients positive by ST but negative by AS, five were ST positive at the 1+ level; the other five were repeatedly negative by AS and confirmed negative by RAST. On an allergen basis, the ST and AS methods showed an 85% agreement. A subset of 24 patients from the foregoing group was studied for total IgE and allergen-specific IgE with products from both Pharmacia (P) and QUIDEL (Q). In this group of patients, skin test results gave seven patients negative and 18 patients positive to one or more allergens. While the overall Total IgE results were higher for ST patients, the Total IgE results alone did not effectively discriminate between ST-positive and ST-negative patients. The allergen-specific, however, results by both methods showed excellent agreement with the ST results.(ABSTRACT TRUNCATED AT 250 WORDS)