Allergen specific IgE measured by the Immunocap™ system is typically reported in KIU/mL as well as in percent of a single standard (ASM system). Abnormal results in one scoring system may coexist with normal results in the other system.

184 patients evaluated for allergic disease underwent serological testing for specific IgE. Results for pollens of the Fagales trees, oak (Quercus alba) and birch (Betula verrucosa) were examined with respect to RAST class scores using the CAP™ KIU/mL system and with the alternative scoring system (ASM).

For both tree pollens, there were 11% more patients who had positive RAST scores utilizing the ASM system compared with the CAP system. High and very high CAP™ scores (>=levels 3) correlated well with ASM class (>=4 scores). However moderate (level 2) CAP™ scores could be either ASM RAST class 2 or 3, and negative (level 0) CAP™ scores were mostly ASM RAST class 0 but sometimes were class 1. Considering all patients with either oak or birch positive RAST scores, the proportion of RAST scores which were discordantly positive for only one Fagales tree was similar utilizing the 2 scoring methods.

For 2 tree pollens which characteristically elicit strong IgE responses, a higher proportion of positive results are noted when RAST results are scored using the ASM system, mostly due to ASM class 1 increases.