Prevalence of IgE to natural rubber latex in unselected blood donors and performance characteristics of AlaSTAT testing

Background: The prevalence of IgE to natural rubber latex (NRL) proteins in the general population remains unsettled, both because of the difficulty o f obtaining an unbiased population representative of the general population of the United States and because of concerns about the reproducibility of tests for anti-latex IgE antibodies. Establishing the prevalence in the pop ulation is important toward defining the potential risks of persons enterin g areas where latex exposure may occur. Objective: The purposes of this study were to determine the prevalence of I gE to latex in a general population and to assess the performance character istics of the AlaSTAT microtiter plate test for anti-latex IgE when perform ed independently by different laboratories. Methods: One thousand nine hundred and ninety-seven consecutive blood sampl es obtained from the Oklahoma Blood Institute were assayed independently in three laboratories for IgE to NRL using the FDA-approved AlaSTAT ELISA for IgE to NRL. The group consisted of 56% men and 44% women. Ninety percent w ere Caucasian, 4% African American, and 6% were "other." Results: The prevalence IgE to NRL between the 3 laboratories varied from 5 .4% to 7.6% at the designated cut off of 0.35 kU/L. Examination of results for specific individuals demonstrated >90% agreement between the three site s with the most reproducible results at the Class II cutoff of greater than or equal to 0.7 kU/L. There was no difference in the percent of positive v alues at the three laboratories, Conclusions: There is good agreement between laboratories as to NRL IgE rea ctive and non-reactive sera using the AlaSTAT test. This report of the larg est sample of blood donors confirms earlier reports as to the prevalence of IgE NRL in blood donors.