Date Published: September 6, 2017
Publisher: BioMed Central
Author(s): Arminda Jorge, Elisa Soares, Emanuel Sarinho, Felix Lorente, Jorge Gama, Luís Taborda-Barata.
The prevalence of adverse food reactions (AFR) has been increasing in the western world. Clinical manifestations are diversified and it may not be possible to clinically discriminate between IgE and non-IgE mediated AFR. In Portugal, the prevalence of AFR and food allergies in children is not known. Thus, the objectives of this study were to determine the prevalence of AFR in central Portugal.
Point prevalence study in 3–11 year-old schoolchildren from Central Portugal. Food-related questionnaires, skin prick tests (SPT) with foods and determination of food-specific IgE levels were performed.
Of 4045 schoolchildren, 2474 (61.2%) accepted to be included in the study. Global prevalence of AFR was 7.1% (95% CI 6.2–8.1), based upon the initial questionnaire, 4.6% (95% CI 3.9–5.5), based upon a confirmatory questionnaire and the prevalence of probable food allergy (IgE-associated AFR: positive history + positive SPT and/or positive specific IgE) was 1.4% (95% CI 0.9–1.9). Most frequently implicated foods were fresh fruits, fish and egg. A first episode at an earlier age, mucocutaneous and anaphylactic reactions were more frequent in IgE-associated AFR.
The prevalence of probable food allergy in 3–11 year old Portuguese children from central Portugal is low and parents over-report its frequency. Most frequently implicated foods were fresh fruit and fish. Immediate type, polysymptomatic, and more severe reactions may commence at an earlier age and be more frequent in IgE-associated than in non-IgE associated reactions.
The online version of this article (doi:10.1186/s13223-017-0212-y) contains supplementary material, which is available to authorized users.
The prevalence of adverse reactions to foods (AFR) has been increasing, particularly in the first years of life [1–3]. According to a recent metanalysis, the prevalence of self-reported food allergies varies between 3 and 35%, depending upon the age group, the geographical area and the methodology used . This broad range of values may have to do with different methodological approaches which were used in the various studies; furthermore, in some of the reports the sample of involved only children followed up in specialty clinics whereas in other studies the values were obtained in the general population of children; finally, in some cases, these self-reported values were backed up by oral provocation studies whereas in other reports, only questionnaire-based results were used. Nevertheless, there is a scarcity of studies carried out in the general population of children.
This report is the first population-based study of the prevalence of adverse food reactions in children in Portugal. We obtained a satisfactory reply rate (61.2%) to the initial questionnaire from the parents of children attending public schools and pre-schools in the centre of Portugal. Prevalence of self-reported adverse food reactions (perceived food allergy) was 4.6%, and the prevalence of probable IgE-associated food allergy (IgE-AFR) was 1.4%.
In conclusion, this first population-based study showed that the prevalence of probable food allergies in children from central Portugal was low and that parents tend to over-report its frequency. Most frequently implicated foods were fresh fruits and fish. Immediate type, polysymptomatic, and more severe reactions may commence at an earlier age and be more frequent in IgE-associated than in non-IgE-associated reactions. Our study has contributed to the characterization of adverse food reactions in Portuguese children.