Study of food allergy on Spanish population

Background: The aim of the study was to investigate the prevalence of food allergy in patients referred to our Allergy Unit and to evaluate the diagnostic methods used. Methods: We selected 674 patients referred to the Allergy Unit of our hospital from May 2002 to October 2004. The prevalence of symptoms was determined by a standardized questionnaire, prick-prick test, and serum specific IgE. In a second phase, double-blind oral challenge tests were administered. Results: Food allergy was found in 106 patients (15.7%): 71 adults (67%) and 35 children (33%). The prevalence of food allergen sensitization was 14% in adults and 20.8% in children. A total of 89.6% of the patients experienced symptoms immediately. Only 29.2 % the patients of sought medical attention and adrenaline was administered to five (16.1 %). The foods most frequently involved in allergic reactions were fruits (56.6 %) and tree nuts (22.6 %).The most common symptoms were oral allergy syndrome (46.2 %), urticaria (32.1 %), and anaphylaxis (14.2 %). Combining the results of the questionnaire with those of prick-prick tests in patients whose allergy was confirmed by double-blind, placebo-controlled food challenge (9.1 %) showed a sensitivity of 95.5 %, a negative predictive value of 96 %, a specificity of 75 % and a positive predictive value of 73 %. Conclusions: 1. The prevalence of food allergy in our sample was 9.1 %. 2. The foods most frequently involved in allergic reactions were fruits and tree nuts. 3. The most common symptoms were oral allergy syndrome, urticaria, and anaphylaxis. 4. Combining our questionnaire with in vivo tests allowed us to diagnose 75-96 % of patients with no food allergy and 95 % of food allergy patients.