Do Residual Wheal Skin Prick Test Responses To Perennial and Seasonal Allergens Correlate With Their Specific IgE Levels In Allergic Subjects?

Abstract

The correlation between allergen specific skin prick tests (SPT) and specific lgE levels in patients allergic to either perennial (cat) or seasonal (ragweed) allergen is, to our knowledge unknown. Our aim was to determine if SPT wheal size could be predictive of IgE level. Data from 1307 subjects (18-65 years old) allergic to either cat or ragweed allergen was analyzed. All subjects had a minimum of one year history of allergy and positive skin prick test to either cat or ragweed allergen of 3 or 5mm. A Spearman Rank Correlation between the SPT wheal response and the corresponding specific IgE was performed. The SPT residual wheal responses analyzed ranged from 3 to 60 mm while the IgE levels ranged from 0 to 466 kU/L. A moderate to low correlation between the allergen specific SPT and IgE was observed (r=0.384). There was a similar correlation between the perennial cat allergies (r=0.346, n=323) compared to the seasonal ragweed allergies (r=0.349, n=984). A SPT response ≥5 was highly likely to yield an IgE class of II or greater, with 94% of the IgE levels being >0.7kU/L. This study demonstrates that allergenicity assessed by SPT and IgE is consistent between perennial and seasonal allergens. SPT response is a reasonable indicator of expected IgE level.