Immunoglobulin E-mediated food allergies among adults with allergic rhinitis

OBJECTIVE: To compare the prevalence of food allergy for peanut, shrimp, and milk in adults with allergic rhinitis and to determine predictive values of these allergens and total immunoglobulin E (IgE) to detect food allergies.

STUDY DESIGN: Cross-sectional study.

SETTING: University of Chicago Medical Center, Chicago, Illinois.

SUBJECTS AND METHODS: We retrospectively analyzed in vitro enzyme-linked immunosorbent assays of adults with rhinitis. Subjects were tested for nine inhalants and three foods (peanut, shrimp, milk) and total IgE. Subjects with food allergy history were tested with additional foods. The sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) of the allergens and total IgE to detect food allergies were calculated.

RESULTS: A total of 283 subjects received in vitro tests. Fortyone percent tested negative and 59 percent tested positive for inhalants. The prevalence of subjects with a positive peanut or shrimp allergy in the inhalant-positive population was significantly greater than subjects with milk allergy (23.4% peanut [P = 0.008], 22.2% shrimp [P = 0.001], and 13.2% milk [P = 0.008], P = 0.001). For subjects with food allergy history, peanut had the best SP (100.0%), SE (28.1%), PPV (100.0%), and NPV (64.6%) in detecting allergies to other foods. In patients positive for the initial panel (inhalants and peanut), the SP, SE, PPV, and NPV of elevated total IgE was 71.4, 72.4, 77.8, and 65.2 percent, respectively.

CONCLUSION: Peanut and shrimp were the most common foods encountered in adults with allergic rhinitis. Peanut was best in predicting other food allergies. Total IgE levels with inhalants plus peanut provided the optimal combination of SE, SP, PPV, and NPV. In vitro testing may be important to identify and prevent anaphylaxis to foods in adults.

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