Potential non-immunoglobulin E-mediated food allergies: comparison of open challenge and double-blind placebo-controlled food challenge

A comparison of double-blind, placebo-controlled food challenge and open food challenge

BACKGROUND

Double-blind, placebo-controlled food challenge (DBPCFC) remains the gold standard for diagnosing food allergy, despite sparse comparisons to open food challenges (OpenFCs). The objective of this retrospective study was to compare severity of symptoms and threshold values (cumulative dose of food allergen eliciting a clinical reaction) in children and adults with peanut allergy, challenged in an open and/or double-blind, placebo-controlled protocol.

METHODS

This study included patients from the Allergy Centre, Odense University Hospital with a positive oral food challenge, defined as strict objective signs, with peanut during the period 2001-2022. Severity of symptoms was graded using the Sampson's severity score. Distribution models of threshold values were calculated using log-normal interval-censored survival analysis, and the number of placebo reactions was evaluated.

RESULTS

In total, 318 positive OpenFCs and 86 DBPCFCs were included. There was no difference in severity of symptoms nor threshold values comparing the two challenge types, neither when stratified for age groups. However, a higher proportion of children experienced Grade 3 symptoms in the double-blind group. Only one patient had a positive reaction to a placebo challenge.

CONCLUSION

Our findings do not advocate for DBPCFC being superior to OpenFC, if the latter is performed with strict objective stop criteria by trained staff.

The dilemma of open or double-blind food challenges in diagnosing food allergy in children: Design of the ALDORADO trial

BACKGROUND

It is of major importance to diagnose food allergy accurately. Current guidelines support the use of oral food challenges to do so. The double-blind placebo-controlled food challenge (DBPCFC) has been regarded as the 'gold standard' for decades. However, DBPCFCs are costly, and time- and resource-intensive procedures. Structural implementation of less demanding open food challenges will only find support if research demonstrates that their outcome is comparable to DBPCFC, yet this has been proven difficult to investigate.

METHODS

We performed a literature review to investigate the diagnostic accuracy of oral food challenges and interviewed 19 parents of children with proven or suspected food allergy about the design of a trial to study this.

RESULTS

An overview of the dilemma of diagnosing food allergy using oral food challenges, and the methodological issues and parents' opinions to study this. No comparative studies have been performed using the latest guidelines on oral food challenges.

CONCLUSIONS

There is an urgent need to investigate the diagnostic accuracy of different oral food challenge protocols. We present the rationale and design of the ALDORADO trial (ALlergy Diagnosed by Open oR DOuble-blind food challenge) that has been set up to investigate whether the outcome of the open food challenge is comparable to DBPCFC.

Food Allergy in Korean Patients with Chronic Urticaria

Background

The etiology of chronic urticaria (CU) remains unknown in most patients. Possible causes in some cases include food, but the role of allergy to food antigens in patients with CU remains controversial.

Objective

The aim of this study was to evaluate the association between food allergy and CU.

Methods

Korean patients with CU were assessed for a previous history of food allergy that caused symptoms of CU. Blood samples were taken from 350 patients to measure food allergen-specific IgE. Based on history and laboratory results, open oral food challenge (OFC) tests were performed.

Results

Of 350 participants, 46 (13.1%) claimed to have experienced previous food hypersensitivity. Pork (n=16) was the main food mentioned, followed by beef (n=7), shrimp (n=6), and mackerel (n=6). We found that 73 participants (20.9%) had elevated levels of food-specific IgE, with pork (n=30), wheat (n=25), and beef (n=23) being the most common. However, when the open OFC tests were conducted in 102 participants with self-reported food hypersensitivity or raised levels of food-specific IgE, only four participants showed a positive reaction to pork (n=3) or crab (n=1).

Conclusion

Although some participants claimed to have a history of CU related to food intake, when an open OFC test was conducted, few of them had positive results. We therefore conclude that food allergy is an uncommon cause of chronic CU.

Safety of intradermal skin tests for inhalants and foods: a prospective study

BACKGROUND

Intradermal skin testing is a useful allergy diagnostic tool. Although considered safe when properly performed, systemic reactions have been reported. This is the first large, prospective study to record and evaluate all systemic reactions from intradermal skin testing (IDT) to inhalant or food antigens.

METHODS

A 24-month prospective study by 40 physician practices, recording all IDT tests, including reactions, symptoms, severity, time after injection, and reaction treatments.

RESULTS

Eighty systemic reactions (22 major) occurred among 20,530 patients (878,583 wheals). Nine had epinephrine treatment, 4 were observed in an emergency department, and there were no hospitalizations or fatalities. The overall systemic reaction risk was 0.009%. The risk of having a major reaction was 0.003%, or 1 reaction per 933 patients.

CONCLUSION

Intradermal skin tests for inhalants or foods, when performed with appropriate precautions, have a safety profile comparable to skin prick tests.

The allergic march: can we prevent allergies and asthma?

The allergic march is a progression of atopic disease from eczema to asthma, and then to allergic rhinoconjunctivitis. It appears to be caused by a regional allergic response with breakdown of the local epithelial barrier that initiates systemic allergic inflammation. Genetic and environmental factors predispose to developing the allergic march. There are data to support 4 possible interventions to prevent the allergic march from progressing to asthma: (1) supplements of dietary probiotics, (2) exclusive breast feeding during the first few months of life, or, alternatively (3) use of extensively hydrolyzed infant formulas, (4) treatment with inhalant allergen immunotherapy by either subcutaneous or sublingual methods.