Adverse reactions to foods and food allergy: development and reproducibility of a questionnaire for clinical diagnosis

Prevalence of reported food allergies in Brazilian preschoolers living in a small Brazilian city

Introduction

Although the prevalence of allergic diseases, including food allergies, has increased over recent decades, relevant information on this topic is still lacking, particularly in younger children living in small cities.

Objective

To investigate the prevalence of reported food allergies in preschoolers in Limoeiro/Pernambuco, Brazil.

Methods

This was a cross-sectional study with preschoolers. Parents/guardians of all preschoolers enrolled at municipal schools between March and June 2019 (total of 619) were invited to complete a screening questionnaire (total of 619). Another 151 questionnaires were applied on the streets of the town. For positive responses, a second, more detailed and validated questionnaire was completed.

Results

A total of 412 questionnaires were returned, of which, 47 presented a positive response to food allergies and only 29 (7.04%) identified a particular food. The most frequently reported food items were shrimp, mollusks, pork, fruit and milk. Of the 29 who identified foods, 22 responded to the detailed questionnaire, resulting in only 4 (0.97%) positive responses. Of these, two were later discarded through clinical examinations and an open oral provocation test, resulting in a final prevalence of 0.48% of confirmed food allergies.

Conclusion

The prevalence of reported food allergies was lower than that described in previous studies. The most commonly mentioned foods were shrimp, mollusks and pork, with more reports of multiple food allergies, even in children who had never been previously exposed to these possible allergens, which highlights the relevance of perception in reported food allergy studies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-022-00710-1.

Development of a screening questionnaire for the study of food allergy in adults

Background & aims

As far as we know, no screening questionnaire has been developed and validated for identification of adverse food reactions in Portuguese-speaking adults, as an initial approach towards the investigation of cases of possible food allergy. Thus, the objective of this study was to develop and validate a screening questionnaire of food allergy in adult Portuguese-speaking patients.

Methods

This was a multicentre, cross-sectional study using a simple random sample of 186 adults between 18 and 82 years old from various parts of the centre of Portugal. Intelligibility of the questionnaire was first assessed in 24 patients with confirmed IgE- or non-IgE-mediated food allergy, and in 24 volunteers without food allergies. The 17-item questionnaire was subsequently applied by phone to 78 food allergic patients (66 IgE-mediated and 12 non-IgE mediated) and to 60 non-food allergic volunteers, with subsequent reassessment (re-test). Face and content validity, intelligibility, construct validity, and test-retest reliability (temporal stability) were analysed.

Results

Face and content validity allowed item reduction from 30 to 17 items with adequate content validity index >0.78. Construct validity was confirmed in the 66 confirmed IgE-mediated food allergic patients, 12 non-IgE-mediated food allergic patients, and 60 non-allergic patients. Test-Retest Reliability (general temporal stability) of the test had a Spearman correlation coefficient value of 0.845 for the retest. Cohen's Kappa values for the relevant questions were greater than 0.890 for almost all items. No differences were found when sex, age, and volunteers' recruitment origin were analysed. An inverse relationship was found between reliability and retest time interval.

Conclusions

Due to the quick and easy implementation, confirmation of face, content and construct validity as well as high temporal reproducibility, this screening questionnaire may be a useful study tool for an initial approach to detection of food allergies in adults.

Development of a tool for screening adverse food reactions and food allergy in Portuguese children

INTRODUCTION AND OBJECTIVES

A standardised questionnaire may be an excellent tool for epidemiological studies aiming at screening children with suspected food allergies. Thus, the aim of the present study was to develop a screening questionnaire for assessing children with suspected food allergy and to analyse its reproducibility.

MATERIALS AND METHODS

A questionnaire of adverse food reactions was developed by literary review of similar questionnaires validated in other countries as well as less well defined, non-validated Portuguese questionnaires. Peer review of the questionnaire by a panel of specialists and subsequent exploratory analysis was carried out by applying the questionnaire in children with confirmed food allergy. Test-retest analysis was performed by giving a face-to-face questionnaire to 159 children with suspected adverse food reactions, aged between three and 11 years. Temporal stability using Spearman Rho correlation test and reproducibility was studied using Cohen's Kappa index.

RESULTS

115 children confirmed adverse food reactions that occurred with one or more foods. Retest was given about three weeks after the test, to 50 of these children who were randomly selected. The questionnaire showed good temporal stability (Spearman correlation coefficient of 0.834), and good reproducibility (only two of the 27 items had a Kappa index <0.60).

CONCLUSIONS

This questionnaire showed good temporal stability and reproducibility. Its validation for screening children with suspected food allergy will allow a standardised approach to diagnosis and comparison of results obtained in different centres.

Prevalence and clinical features of adverse food reactions in Portuguese children

Background

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.

Methods

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.

Results

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.

Conclusions

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.

Electronic supplementary material

The online version of this article (doi:10.1186/s13223-017-0212-y) contains supplementary material, which is available to authorized users.

Adult Food Allergy Prevalence: Reducing Questionnaire Bias

BACKGROUND

Food allergy (FA) prevalence has increased in the last decades, but epidemiologic studies could show overestimated results. The objective of this study is to estimate the prevalence of immediate FA in adults in a region of Central Brazil, using a questionnaire to try to reduce misperceptions about FA reaction.

METHODS

A cross-sectional study was conducted, enrolling an adult population aged 18-65 years comprised of families in a Central Brazilian city. In the first phase, participants answered a self-administered questionnaire for FA screening. In the second phase, the participants who reported an FA in the first questionnaire were visited to complete the second questionnaire applied by trained researchers.

RESULTS

Of the 4,916 adults visited, 1,583 returned a completed questionnaire. Reported FA occurred in 171 (10.8%) subjects, and the more frequent citations were cow's milk, pork, fruits, shrimp, and vegetables. One hundred and four of these individuals completed the second questionnaire, and 15 (1.0%) were considered to have an FA diagnosis. The main foods were fruits, followed by cow's milk, shrimp, pork, and vegetables.

CONCLUSION

After use of a specific questionnaire to recognize possible IgE-mediated FAs, a low frequency of FA was considered in this population. Use of a directed questionnaire administered by trained researchers could be an alternative for epidemiological IgE-mediated FA studies to achieve more accurate results.