Food allergy in the Netherlands: differences in clinical severity, causative foods, sensitization and DBPCFC between community and outpatients.

BACKGROUND: It is unknown whether food allergy (FA) in an unselected population is comparable to those from an outpatient clinic population. OBJECTIVE: To discover if FA in a random sample from the Dutch community is comparable to that of outpatients. METHODS: This study was part of the Europrevall-project. A random sample of 6600 adults received a questionnaire. Those with symptoms to one of 24 defined priority foods were tested for sIgE. Participants with a positive case history and elevated sIgE were evaluated by double-blind placebo-controlled food challenge (DBPCFC). Outpatients with a suspicion of FA were evaluated by questionnaire, sIgE and DBPCFC. RESULTS: In the community, severe symptoms were reported less often than in outpatients (39.3% vs. 54.3%). Participants in the community were less commonly sensitized to any of the foods. When selecting only those with a probable FA (i.e. symptoms of priority food and elevation of sIgE to the respective food), no major differences were observed with respect to severity, causative foods, sensitization and DBPCFC between the groups. CONCLUSION: In the Netherlands, there are large differences in self-reported FA between community and outpatients. However, Dutch community and outpatients with a probable FA do not differ with respect to severity, causative foods, sensitization and DBPCFC-outcome.

The prevalence of plant food allergies: a systematic review.

BACKGROUND: There is uncertainty regarding the prevalence of allergies to plant food. OBJECTIVE: To assess the prevalence of allergies to plant food according to the different subjective and objective assessment methods. METHODS: Our systematic search of population-based studies (since 1990) in the literature database MEDLINE focused on fruits, vegetables/legumes, tree nuts, wheat, soy, cereals, and seeds. Prevalence estimates were categorized by food item and method used (food challenges, skin prick test, serum IgE, parent/self-reported symptoms), complemented by appropriate meta-analyses. RESULTS: We included 36 studies with data from a total of over 250,000 children and adults. Only 6 studies included food challenge tests with prevalences ranging from 0.1% to 4.3% each for fruits and tree nuts, 0.1% to 1.4% for vegetables, and < 1% each for wheat, soy, and sesame. The prevalence of sensitization against any specific plant food item assessed by skin prick test was usually < 1%, whereas sensitization assessed by IgE against wheat ranged as high as 3.6% and against soy as high as 2.9%. For fruit and vegetables, prevalences based on perception were generally higher than those based on sensitization, but for wheat and soy in adults, sensitization was higher. Meta-analyses showed significant heterogeneity between studies regardless of food item or age group. CONCLUSION: Population-based prevalence estimates for allergies to plant products determined by the diagnostic gold standard are scarce. There was considerable heterogeneity in the prevalence estimates of sensitization or perceived allergic reactions to plant food.

The prevalence of food allergy: a meta-analysis.

BACKGROUND: There is uncertainty about the prevalence of food allergy in communities. OBJECTIVE: To assess the prevalence of food allergy by performing a meta-analysis according to the method of assessment used. METHODS: The foods assessed were cow's milk, hen's egg, peanut, fish, shellfish, and an overall estimate of food allergy. We summarized the information in 5 categories: self-reported symptoms, specific IgE positive, specific skin prick test positive, symptoms combined with sensitization, and food challenge studies. We systematically searched MEDLINE and EMBASE for publications since 1990. The meta-analysis included only original studies. They were stratified by age groups: infant/preschool, school children, and adults. RESULTS: A total of 934 articles were identified, but only 51 were considered appropriate for inclusion. The prevalence of self-reported food allergy was very high compared with objective measures. There was marked heterogeneity between studies regardless of type of assessment or food item considered, and in most analyses this persisted after age stratification. Self-reported prevalence of food allergy varied from 1.2% to 17% for milk, 0.2% to 7% for egg, 0% to 2% for peanuts and fish, 0% to 10% for shellfish, and 3% to 35% for any food. CONCLUSION: There is a marked heterogeneity in the prevalence of food allergy that could be a result of differences in study design or methodology, or differences between populations. CLINICAL IMPLICATIONS: We recommend that measurements be made by using standardized methods, if possible food challenge. We need to be cautious in estimates of prevalence based only on self-reported food allergy.