High Prevalence of Skin Test Positivity in Severe or Difficult-to-Treat Asthma

Background: Skin tests are considered the gold standard for detecting allergen-specific immunoglobulin E (IgE) in the clinical setting and are an important tool for diagnosing and managing allergic asthma. Objective: To assess the prevalence of skin testing in patients ≥ 12 years enrolled in The Epidemiology and Natural History of Asthma: Outcomes and Treatment Regimens (TENOR) study. Methods: Patients were asked whether they had ever been skin tested and, if so, they were asked to provide the test results. Clinical characteristics were used to compare positive (ST+), negative (ST?), and skin test not done (STND) patients. Results: Of 2,985 patients eligible, 85.8% recalled being skin tested. Of those tested, 93.5% were positive (allergist 95.7%, pulmonologist 87.3%). A high proportion of Whites (93.5%) and non-Whites (94.0%) were ST+; however, more non-Whites had never been skin tested (21.7% vs. 12.3%, respectively; p < 0.0001). Total serum IgE was 104.6 IU/mL for ST+ patients, 87.1 IU/mL for STND patients, and 32.4 IU/mL for ST? patients. Age at asthma onset, duration of asthma, and the prevalence of atopic disorders and asthma triggers differentiated the ST+ from the ST? group. Disease severity appeared similar between the two groups. In general, values for STND patients were closer to the ST+ group, suggesting that those not tested would have been ST+ if administered a test. Conclusions: The prevalence of ST+ patients was high in allergy and pulmonology practices, and in White and non-White patients. These data support the utility of a more complete allergic evaluation in severe asthmatics. Skin testing appears associated with disease pathophysiologies in asthma.