Role and interpretation of total serum IgE measurements in the diagnosis of allergic airway disease in adults

Background: While total IgE measurements are often used in clinical practice, it is unclear how they should be interpreted for the diagnosis of allergic disorders. We studied whether total IgE may be used to rule out or predict sensitization and whether there are age or gender differences.Methods: ROC curves were assessed in subjects with asthma or allergy symptoms from a general population sample. We studied predictive values and likelihood ratios. At least one positive skin test (Phazet(R)) or specific IgE measurement (CAP(R)) served as reference.Results: High negative predictive values, suitable to rule out sensitization, were not found. In younger subjects, high total IgE levels strongly increase the probability of sensitization. The relationship between monosensitization and total IgE was less strong, but meaningful positive likelihood ratios were found at higher levels of total IgE. The discriminating ability of total IgE was better in the age group 20-44 than 45-70 years and comparable in males and females.Conclusion: Total IgE is not useful to rule out sensitization to common inhalant allergens. High total IgE may indicate a high probability of sensitization and may be useful to decide whether further investigation is warranted in patients with negative specific allergy tests to a panel of common inhalant allergens.