The relationship between total IgE and specific antibody testing by Immunocap in screening allergic asthma

Abstract

In a bid to reduce the number of tests required to diagnose allergic asthma among adult asthmatic patients, we investigated the relationship between the value of the total serum IgE and number of positive specific antibodies on Immunocap testing in a cohort of 566 asthmatic subjects.

This study is retrospective. Total IgE level and the amount of positive antibodies to common aeroallergens on the Immunocap test of each patient were recorded from their charts. A positive Immunocap result was set at level II (an antibody titer of ≥0.56kU/L) and we found the following: 386 subjects had complete data and were analyzed. 180 subjects had no positive Immunocap test while 206 of them had at least one positive Immunocap test according to our set threshold. The mode of the number of positive Immunocap tests was 2 (12% of the analyzed subjects). Pearson correlation between number of positive Immunocap results and total IgE for each patient was significant (P<0.0001, R=0.45). Figure 1 shows the percentage of Immunocap positive patients for different total IgE thresholds between 10 to 100.

Conclusions:

1. At a total IgE level of 10KU/L in adult population, 11.6% of the subjects still have a positive specific IgE antibody testing.

2. A low total IgE result should not preclude checking for specific IgE level in subjects suspected to have allergic asthma.

3. We recommend that subjects with total IgE of less than 30 KU/L may not benefit from specific antibody screening tests except when they are being considered for immunotherapy.