The relationship between seroatopy and symptoms of either allergic rhinitis or asthma

Background: Epidemiologic data on allergic rhinitis and asthma are frequently based on self-reported symptoms. Objective: This cross-sectional study examined the relationship between self-reported symptoms and histories of allergic rhinitis or asthma and a marker of allergic sensitization, allergen-specific IgE. Methods: We surveyed 702 pregnant women in Michigan. Blood samples were analyzed for specific IgE to 9 allergens: dust mites (Dermatophagoides farinae and Dermatophagoides pteronyssinus), cat, dog, cockroach, ragweed, timothy grass, egg, and Alternaria alternata. Seratopy was defined as a specific IgE greater than or equal to 0.35 kU/L to any allergen. Results: Seroatopy was found in 66.7% of those with hay fever symptoms, 68.3% with a physician's diagnosis of asthma, and 72.1% of those with both conditions. These results differed significantly from asymptomatic subjects, where 49.8% of patients without hay fever and 50.4% without asthma were seroatopic. Race and education did not modify the relationships. Symptoms related to specific exposures were modest predictors of positive specific IgE to related allergens (positive predictive values from 26.5% to 50.3%). Conclusion: Self-reported symptoms of allergic rhinitis or asthma were significantly associated with allergic sensitization, but the odds ratios were of relatively low magnitude for this historical information to be considered evidence of current allergic sensitization. A 66% to 68% probability existed that those with symptoms of allergic rhinitis or asthma would have a positive specific IgE test. Clinical implications: Self-reported histories of hay fever or asthma alone are only modest predictors of allergic sensitization. When knowledge of allergic sensitization is important, information beyond self-reported symptoms is necessary.