A multi-allergen screening test for suspected allergic disease in coloured children

The measurement of total serum IgE levels is widely used as a screening test for allergic disease but lacks specificity in South African subjects because of the presence of ethnic and environmental factors, e.g. parasite infestation, which also raise total serum IgE. The reliability of a new in vitro multi-allergen test, Phadiatop (Pharmacia), which is not influenced by parasitic infestation, was investigated as a screen for allergic disease in coloured children. Phadiatop assays and total serum IgE levels performed on 18 children with known allergic disease were compared with 21 non-allergic individuals. All the allergic, but only 2 of the non-allergic children had a positive Phadiatop result (P = less than 0.01; chi-square test) but there was no significant difference between the number of allergic or non-allergic children with elevated total serum IgE levels (P = greater than 0.1). The Phadiatop test demonstrated a specificity of 90% compared with 28% for total serum IgE. The predictive value of a negative Phadiatop result was 90% compared with 54% for total serum IgE levels. These data indicate that the Phadiatop test is a more specific screening test for allergic disease than total serum IgE levels in coloured children.