Annual Meeting of the European Academy of Allergology and Clinical Immunology (vol 52, pg 158, 1997)

It was the aim of this study to assess the diagnostic value of bronchial challenge tests using flour dust inhalation from capsules by a Spinhaler, and to compare this method quantitatively with bronchial challenge tests using a commercially available wheat flour extract for the diagnosis of bakers' asthma. 34 bakers with work-related symptoms of rhinitis or asthma, as well as 10 atopic controls were examined. Subjects were randomized to inhale either 0.01, 0.1, 1, 10 and 100 mg/ml of an aqueous wheat flour extract by tidal volume breathing for 10 minutes, or wheat flour dust filled in capsules, respectively One, two, and four capsules of flour dust were given by a Spinhaler (Fisons Inc, UK). 15 (11) bakers demonstrated a greater than or equal to 50% fall of specific airway conductance (sGaw) after the inhalation of the wheat flour extract (dust). 3 controls had a positive reaction with the extract, whereas dust inhalation did not cause positive bronchial reactions in controls. 17 bakers, but also 2 controls demonstrated a positive skin test to wheat flour (wheal greater than or equal to 3 mm). Using a 50% fall of sGaw as criterion for a positive bronchial provocation test, sensitivity for the extract or dust inhalation was 0.44 and 0.32, and specificity was 0.7 and 1.0. If only subjects with a positive skin test with wheat flour were considered, sensitivity of both tests was 0.65. ROC plots using different definitions of the gold standard revealed a similar validity of both methods. If a 30% fall of sGaw was used as positivity criterion, the sensitivity of the Spinhaler method increased to 0.76, and the validity was higher than that of the extract inhalation. We conclude that the validity of bronchial challenge tests using wheat flour dust inhaled from Spinhaler capsules was superior to tests using a commercially available aqueous wheat flour extract. The higher specificity of the Spinhaler method might be an advantage if bronchial challenge tests are used as confirmation tests.