Double blinde plasebo controlled food challenge test on banana allergy

Food allergy is defined as an abnormal or an exaggerated immune response against food proteins. Genetical and environmental factors play major role in this complex disease group. Immunological food allergy is derived from the mechanisms which may or may not be mediated by IgE. Story of the allergy developed after the food ingestion is important for the diagnosis of the IgE mediated food allergies. However there may be a cross reaction between foods and pollens. After eliminating the food suspected for allergy, withdrawal of the symptoms is valuable for the diagnosis. If elimination is succesful, diagnosis should be confirmed by challenge test. Oral food challenge test is the key for defining the specific food. Double-blind placebo controlled food challenge (DBPCFC) is required for definitive diagnosis. In our study, we aimed to study DBPCFC in the patients who describe reaction with banana and have high level of banana specific IgE . We determined reactions in the 13% of DBPCFC patients. Cut-off value was determined as 0,66 kU/L for banana specific IgE and sensitivity and specificity was 83% and 51%, respectively. Positive predictive value for specific IgE was 20%, while it was 96% for negative predictive value. Sensitivity and specificity for banana P+P was 33% and 93%, respectively; positive predictive value was 40% and 91% for negative predictive value. This is the firs study using the DBPCFC test to diagnose the banana allergy. Up to now, positive predictive value was not defined for banana specific IgE. Our study showed that, specific IgE or skin tests alone are not adequate for the diagnosis of food allergy, and to define subjective symptoms related with food and to determine cross reactions, DBPCFC tests should be done for confirmation.