Epidemiology, diagnosis and management of food allergy

Abstract

This thesis describes the epidemiology, diagnosis and management of food allergy. Epidemiology This thesis shows that the prevalence of self-reported adverse food reactions in children and adults was high: 17-25% for all foods and 10-11% for 24 preselected, so-called priority foods. The prevalence of probable food allergy, defined by suggestive history and positive IgE for priority food, was much lower: 2.3% for children and 4.1% for adults. In adults, the prevalence of true food allergy confirmed by double-blind placebo-controlled food challenge (DBPCFC) was 3.2%, which is higher than the 2.4% found in a previous Dutch study in 1989. In the Netherlands, the most common foods causing an allergy in children and adults are fruits (apple, kiwi, peach), nuts (hazelnut, walnut) and peanut. Peanut and hazelnut more frequently cause severe reactions compared to fruits, but fruits can also cause anaphylactic reactions. Changing eating habits may play a role in the development of food allergy. Kiwifruit is relatively recently introduced on the European market and now a common cause of food allergy. Kiwifruit allergy across Europe was investigated, showing that sensitization to the stable allergen Act d 1 and living in Iceland, were associated with a severe kiwifruit allergy. Diagnosis Food allergy diagnosis can be supported by the detection of food-specific sensitization by skin-prick-test or by serum IgE (ImmunoCAP). DBPCFC is the gold standard, but expensive, time-consuming and burdensome for patients. Therefore, it is necessary to improve the diagnostic value of other tests. Two items from medical history (oral allergy symptoms and pollen allergy) were strongly associated with a probable food allergy in The Netherlands. Depending on the food and country involved, component resolved diagnosis (i.e. analysis of sensitization to individual allergens) may be helpful in predicting clinical reactivity and severity . To screen for food allergy, the fx5 ImmunoCAP is frequently used, which detects IgE for six foods. However, the most common food allergens causing food allergy in Dutch adults (i.e. hazelnut and apple) are absent from this food mixture. So, in adults with a suspected pollen-related food allergy, it would be best to test individual allergens based on medical history instead of food mixtures. Management Food allergy is one of the most important causes of anaphylaxis. Epineprhine is the first line treatment for patients with anaphylaxis. Management of food allergic reactions is suboptimal by patients, GPs, at emergency departments and schools. A severe or anaphylactic reaction is often not recognized, there is underuse of epinephrine, the observation period is too short, and at discharge epinephrine is only prescribed to a minority of patients. Proper advice about the use of epinephrine, allergen avoidance and referral to an allergy specialist is often missing. Management of food allergy in schools across Europe was also suboptimal. Conclusion In summary, this thesis shows that the prevalence of perceived food allergy is much higher than of true food allergy. Both diagnosis and management of food allergy can be improved.