Sensitivity of the skin prick test and specificity of the serum-specific IgE test for airway responsiveness to house dust mites in asthma.

BACKGROUND: The concept that asthma diagnosis based on allergen-specific IgE levels in serum is more accurate than diagnosis based on skin test reactivity is controversial. OBJECTIVE: To determine the atopy parameter that correlates most closely with airway reactivity to house dust mites in asthma. METHODS: Forty-three asthma cases were examined retrospectively for data on Dermatophagoides farinae-specific bronchoprovocation, serum-specific IgE, and skin prick tests. RESULTS: The maximal decreases in FEV1 following bronchoprovocation were correlated significantly with both the IgE levels and skin test scores. The accuracies of the tests were highest at a cutoff value of class 4 or higher for the IgE and of 3+ or higher for the skin test. At the cutoff values, the accuracies of both tests were similar (70% vs. 70%). The sensitivity of the skin test (81%) was higher than that of the IgE test (67%), whereas the specificity of the IgE test (71%) was higher than that of the skin test (52%). The sensitivity of the skin test was 91% at 2+ or higher, and the specificity of the IgE test was 95% at class 6 or higher. CONCLUSION: These results suggest that both the specific IgE level and the skin test reactivity are useful parameters in the prediction of positive airway responses to house dust mites in asthma. However, the skin test is more sensitive, whereas the IgE test is more specific. Therefore, these tests can be used in a complementary fashion (i.e., the skin test for screening and the specific IgE test for confirmation of the relevant allergen).