Diagnostic Evaluation of Type I Latex Allergy

Background: Latex hypersensitivity affects a significant number of health care workers. No universally accepted method for the diagnosis of latex allergy is currently available in the United States. Objective: Determine the accuracy of clinical assessment in predicting type I latex allergy, and compare the ability of various latex skin test preparations and in vitro assays in confirming the diagnosis of latex allergy. Methods: Subjects were classified into "history positive," "history ambiguous," or "history negative" based on reports of clinical symptoms. Skin prick tests were performed with ammoniated latex and glove extracts. Sera were analyzed for latex-specific IgE using the Pharmacia CAP and DPC AlaSTAT assays. Results: A total of 207 subjects had histories taken, skin testing, and blood drawn. Out of 49 type I latex-allergy "history positive," 42 (86%) were skin test positive, and 24 (49%) were serum positive. Fifty-nine subjects were latex allergy "history ambiguous." In this group, skin testing showed 19 (32%) positives, and latex-specific IgE were detected in 10 (17%). Out of 99 latex "history negative," 9 (9%) were skin test positive, and 11 (11%) were positive for latex-specific IgE. Out of the 61 subjects with IgE symptoms following latex exposure who were skin test positive, a positive in vitro assay was found in 32 (52%). Conclusions: Skin testing is more likely to confirm a positive latex allergy history. Use of raw ammoniated and glove skin testing preparation sources combined adds to the diagnostic sensitivity. AlaSTAT and CAP correlate well with each other and have good negative predictive value, but lack the sensitivity of skin testing. Use of AlaSTAT and CAP assays combined raises the diagnostic sensitivity as compared to using one in vitro test alone.