Specific diagnosis of exogenous bronchial asthma in children.

Twenty-six children with exogenous asthma were studied by case history (CH), skin tests (ST), allergen-specific serum IgE (RAST), basophil histamine release (HR), and bronchial provocation tests (BPT). Nine standardized allergens were used from the following groups: house dust mite, animal dander, pollen, and mould fungi. For each allergen, the same batch was used throughout for all in vivo and in vitro studies, and the tests were carried out in a controlled, double-blinded manner, independent of each other. Different allergen concentrations were used and the results graded on a semi-quantitative scale. Approximately 120 comparable investigations, using in vivo and in vitro tests were carried out, followed by calculations of the sensitivity and specificity for each test alone, as well as for various combinations of tests, at various allergen-concentrations, and compared with the result of BPT, i.e. the true diagnosis. In this way the results could be used to directly compare the diagnostic value of each test, and combinations of tests. In general, a careful CH combined with ST gave the most reliable results. RAST was the most unreliable single analysis. When pollen or mite allergy was suspected, a combination of ST with either RAST or HR gave a further diagnostic reliability. HR as a single analysis did not seem to offer advantages over existing methods. None of the tests, or combinations of tests offered 100% sensitivity and specificity. By altering the concentration of allergen, the sensitivity, or specificity could be increased, but only at the expense of a decrease in the other. BPT is still necessary in many instances when a specific diagnosis is required.