Do Longer Intervals between Challenges Reduce the Risk of Adverse Reactions in Oral Wheat Challenges?

Management of food allergy based on oral food challenge

PURPOSE OF REVIEW

Food allergy is a growing health problem that affects both patients and society in multiple ways. Despite the emergence of novel diagnostic tools, such as component-resolved diagnostics (CRD) and basophil activation tests (BAT), oral food challenge (OFC) still plays an indispensable role in the management of food allergies. This review aimed to highlight the indications and safety concerns of conducting an OFC and to provide insights into post-OFC management based on recent findings.

RECENT FINDINGS

Standardized OFC protocols have regional diversification, especially in Japan and Western countries. Recent studies suggested that the interval between doses should be at least more than an hour. Furthermore, applying a stepwise method tailored to the patient's specific immunoglobulin E level and history of anaphylaxis seems to mitigate these risks. Recent surveys have shown that, following a positive OFC, options other than strict avoidance are also selected.

SUMMARY

OFC serves diverse purposes, yet the risks it carries warrant caution. The stepwise protocol appears promising for its safety. Subthreshold consumption following OFC shows potential; however, further research on its efficacy and safety is required. Management following OFC should be tailored and well discussed between clinicians and patients.

Timing of initial symptom onset during milk and wheat challenges: A retrospective study

BACKGROUND

Allergic reactions to milk appear sooner than those to hen's eggs, irrespective of the total dose of the oral food challenges (OFCs) and type of matrices. The reported median times for the first symptom occurrence are 20-30 min with milk and 50-60 min with eggs. However, allergic reactions due to wheat have not yet been fully investigated.

METHODS

This study retrospectively collected data from OFC for milk and wheat conducted at Sagamihara National Hospital and Sendai Medical Center from 2009 to 2023. The time from the start of the OFC to the onset of symptoms was compared between children with cow's milk and wheat allergy.

RESULTS

Twenty-five and 13 children reacted to single-dose OFCs with milk products equivalent to 25 mL of raw cow's milk or 15 g of udon noodles, respectively. The median ages of patients with positive challenges were 1.4 and 2.8 years for milk and wheat, respectively, and the median times for the first symptom occurrence were 20 min and 53 min, respectively (p = .006).

CONCLUSION

This multicenter study was the first to examine the time of symptom appearance during single-medium-dose milk and wheat challenges. Allergic reactions to wheat appear later than those for milk during OFC. For multiadministration OFC for wheat, the dosing interval should be longer than 60 min. Our findings can help improve the safety of OFCs.

Relationship between serum allergen-specific immunoglobulin E and threshold dose in an oral food challenge

BACKGROUND

Several studies have reported threshold doses for food allergens. However, evidence regarding potential risk factors for low threshold doses is limited. Moreover, the relationship between threshold dose and specific immunoglobulin E (sIgE) levels to causative foods remains unclear. This study examined the relationship and the risk factors for a low threshold dose.

METHODS

We recruited children with food allergies and examined the risk factors for a positive oral food challenge (OFC) with a low threshold dose and anaphylaxis.

RESULTS

We evaluated 2501 children with food allergies (1667 [67%] boys; median age, 4.9 years) to eggs (n = 1096), milk (n = 671), wheat (n = 370), peanuts (n = 258), walnuts (n = 65), and cashews (n = 41). Of these patients, 234 (9%) reacted to ≤30 mg protein of causative foods and 620 (25%) reacted to ≤100 mg protein of causative foods. The sIgE level to causative foods was a significant independent factor for positive OFCs with a threshold dose of ≤30 mg for milk, wheat, and peanuts; ≤ 100 mg for eggs, milk, wheat, peanuts, and cashews; and anaphylaxis from eggs, milk, wheat, peanuts, and walnuts. High sIgE levels to causative foods were associated with a lower threshold dose of the OFC and anaphylaxis during the OFC.

CONCLUSIONS

Approximately 9% of patients reacted to ≤30 mg protein of causative foods. The potential risks of anaphylaxis should be considered during OFCs for patients with elevated sIgE levels.

A 60-minute dosing interval is safer than a 30- or 40-minute interval in oral food challenge

BACKGROUND

The interval between antigen ingestion may influence the safety of oral food challenge tests (OFCs), especially in patients with severe food allergies.

METHODS

This retrospective chart review of OFCs eliciting objective reactions to wheat, egg, and milk that were performed between April 2012 and January 2021 evaluated an equivalent number of low-dose OFCs performed at 30-, 40-, or 60-min intervals. To avoid the influence of the potential allergy severity of the patients, the prediction scores of all intervals were matched. We evaluated the total symptom score (TS), total ingested dose, and the proportions of severe reactions (TS ≥ 30) and adrenaline use.

RESULTS

We analyzed 945 OFCs (wheat, n = 186; egg, n = 561; milk, n = 198). The 60-min OFC had significantly lower TS than the 30- and 40-min OFC methods in wheat (p < 0.001 and p = 0.003, respectively), egg (p < 0.001 for both), and milk (p < 0.001 and p = 0.018, respectively). The total dose in the 60-min method was significantly lower than in the 30-min method (p < 0.001 for all). The proportion of severe reaction (TS ≥ 30) in the 60-min method was significantly lower than that in the 30-min method for the egg and milk OFCs (p = 0.001 and p < 0.001, respectively). There was no difference in the rates of adrenaline injection.

CONCLUSIONS

The 60-min interval is safer than 30- or 40-min intervals in wheat, egg, and milk OFCs in patients with a low threshold dose for food allergy.

Japanese guidelines for food allergy 2020

Five years have passed since the Japanese Pediatric Guideline for Food Allergy (JPGFA) was first revised in 2011 from its original version. As many scientific papers related to food allergy have been published during the last 5 years, the second major revision of the JPGFA was carried out in 2016. In this guideline, food allergies are generally classified into four clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type of food allergy (urticaria, anaphylaxis, etc.), and (4) special forms of immediate-type of food allergy such as food-dependent exercise-induced anaphylaxis and oral allergy syndrome (OAS). Much of this guideline covers the immediate-type of food allergy that is seen during childhood to adolescence. Infantile atopic dermatitis associated with food allergy type is especially important as the onset of most food allergies occurs during infancy. We have discussed the neonatal and infantile gastrointestinal allergy and special forms of immediate type food allergy types separately. Diagnostic procedures are highlighted, such as probability curves and component-resolved diagnosis, including the recent advancement utilizing antigen-specific IgE. The oral food challenge using a stepwise approach is recommended to avoid complete elimination of causative foods. Although oral immunotherapy (OIT) has not been approved as a routine treatment by nationwide insurance, we included a chapter for OIT, focusing on efficacy and problems. Prevention of food allergy is currently the focus of interest, and many changes were made based on recent evidence. Finally, the contraindication between adrenaline and antipsychotic drugs in Japan was discussed among related medical societies, and we reached an agreement that the use of adrenaline can be allowed based on the physician's discretion. In conclusion, this guideline encourages physicians to follow the principle to let patients consume causative foods in any way and as early as possible.

Innovation in Food Challenge Tests for Food Allergy

PURPOSE OF REVIEW

This review incorporates findings from studies of oral food challenges (OFC) over the last decade and highlights the latest innovations and understanding of the procedure.

RECENT FINDINGS

PRACTALL guidelines are widely used in OFC research, but there is still no international consensus on the OFC protocol in clinical practice. Guidelines for performing OFC in clinical practice have been updated to include oral food challenges for infants. There have been advances in predictive models for outcomes and severity of reaction during OFC that take into account multiple clinical data as well as newer laboratory modalities. Low-dose OFC and eliciting threshold dose determination are being examined for additional diagnostic and therapeutic use in the management of food allergy. Quality-of-life considerations have also been reviewed, as well as post-OFC assessment and care. The OFC remains an important diagnostic tool in the management of food allergy and in clinical research. Advances in the field should improve safety and broaden the clinical applications of this essential procedure.

Follow-up of patients with uncertain symptoms during an oral food challenge is useful for diagnosis

BACKGROUND

Uncertain symptoms often emerge during an oral food challenge (OFC), and Open-OFCs with those uncertain mild symptoms are ordinarily regarded as positive. Double-blind placebo-controlled food challenges should be conducted to determine these associations. Nevertheless, studies regarding the diagnosis of uncertain food allergy symptoms are lacking. We examined the diagnostic decision for a food allergy based on uncertain symptoms during an Open-OFC.

METHODS

We conducted an Open-OFC between August 2005 and April 2012 with 2271 cases who suspected as allergic to hen's eggs, cow's milk, or wheat. For the primary diagnosis, Open-OFCs with obvious symptoms were classified as "positive," no symptoms as "negative," and uncertain, indeterminate symptoms as "uncertain." We encouraged the children in the uncertain group to consume the causative foods at home more than twice; if any definitive symptoms were induced, children were classified as "intolerant," and children without any symptoms were classified as "tolerant," for the final diagnosis.

RESULTS

We analyzed 454 uncertain cases excluding 781 positive cases and 1036 negative cases. The symptoms that occurred for the uncertain cases included slight abdominal pain, localized skin rash, and an isolated cough. Of these cases, 362 (79.7%) were considered tolerant at the final diagnosis. Of the intolerant children at the final diagnosis, the induced symptoms at home were not serious.

CONCLUSIONS

Monitoring of recurring symptoms following consumption of causative foods at home by patients with uncertain symptoms improves the diagnostic accuracy of an Open-OFC.

Evaluation of the results of oral food challenges conducted in specialized and general hospitals

BACKGROUND

Oral food challenge (OFC) tests are conducted in both specialized institutions and general hospitals. We aimed to compare the severity of the conditions of the patients between these 2 types of institutions in order to consider the role of such institutions in society.

OBJECTIVE

We evaluated the results of OFC tests for hen's egg, cow's milk, and wheat that were conducted in a specialized institution (Aichi Children's Health and Medical Center [ACHMC], n = 835) and in 4 general hospitals (n = 327) in Aichi prefecture, Japan.

METHODS

The symptoms provoked were scored using the total score (TS) of the Anaphylaxis Scoring Aichi scoring system in combination with the total ingested protein dose (Pro) before the appearance of allergic symptoms.

RESULTS

The total ingested dose of the challenge-positive patients in ACHMC was significantly less than that in the general hospitals (p < 0.01). The median TS of the provoked symptoms in ACHMC and the general hospitals did not differ to a statistically significant extent in the hen's egg or cow's milk challenges; however, the median TS in ACHMC was significantly lower than that in the general hospitals for the wheat challenge (p = 0.02). The median TS/Pro values in ACHMC were almost identical to the upper 25% of the TS/Pro values in the general hospitals, suggesting that the specialized institution usually managed more severe patients.

CONCLUSION

The specialized institution performed OFC tests at a lower threshold dose, but provoked similar TSs to the general hospitals. This evaluation may help in optimizing the distribution of patients to general hospitals and specialized institutions.

Safety and feasibility of heated egg yolk challenge for children with egg allergies

BACKGROUND

Hen's egg allergy is a frequent cause of childhood food allergy. Egg yolk is used in various commonly consumed foods; if children with allergy to hen's egg could eat heated egg yolk, their quality of life (QOL) would improve. No reports exist regarding oral food challenges (OFCs) for heated egg yolk. We aimed to clarify whether pediatric patients allergic to hen's egg could consume heated egg yolk.

METHODS

Data from pediatric patients who had undergone OFCs for heated egg yolk were evaluated retrospectively.

RESULTS

Among 919 patients, positive OFC results were obtained in 17.0% of patients; seven presented with severe symptoms. Older age, high specific IgE value for ovomucoid, low total IgE levels, and history of anaphylaxis related to food other than hen's egg were risk factors for positive OFC results. Specific IgE values for egg white, ovomucoid, and egg yolk, indicative of a negative predictive value >95%, were 0.71, 0.41, and 0.17 kU_A /l, respectively. A specific IgE to ovomucoid levels of 100 kU_A /l predicted heated egg yolk-positive OFCs for 38.3% of patients. Among 763 patients with a negative OFC, seven (0.9%) reacted to heated egg yolk at home, and 756 (99.1%) consumed hen's egg yolk safely.

CONCLUSIONS

Most pediatric patients allergic to heated hen's egg safely consumed heated egg yolk. Heated egg yolk OFCs rarely provoked severe symptoms and may be recommended for improving the QOL of children with allergy to hen's egg.

Risk Factors for Severe Reactions during Double-Blind Placebo-Controlled Food Challenges

BACKGROUND

Severe anaphylactic symptoms can occur during oral food challenges (OFCs). Thus, high-risk patients (e.g., patients with a history of anaphylaxis or high antigen-specific immunoglobulin E [IgE] levels) must carefully undergo OFCs in hospitals. We attempted to identify the risk factors for severe symptoms during OFC testing among high-risk patients.

METHODS

We retrospectively evaluated patients' characteristics and severe symptoms that were experienced during a double-blind placebo-controlled food challenge test performed before the patients underwent oral immunotherapy between June 2008 and June 2012. Patients were ≥5 years old and had an anaphylactic history or antigen-specific IgE (>30 kUA/L). Severe symptoms were defined using the grading of the Japanese Anaphylaxis Guidelines, which are modified from the European Academy of Allergology and Clinical Immunology Guidelines.

RESULTS

We evaluated 393 cases with positive test results, including 98 cases with severe symptoms. The most frequent severe symptoms were respiratory (77%), gastrointestinal (28%), cardiovascular (27%), and neurological (13%) symptoms. Multivariate analysis revealed that the significant factors for a severe reaction were a history of anaphylaxis to the causative food (adjusted odds ratio [OR]: 2.147, p = 0.003), older age (per 1 year increase, adjusted OR: 1.102, p = 0.044), and an egg OFC (adjusted OR: 0.433, p = 0.003).

CONCLUSIONS

The risk factors for a severe reaction to OFCs were a history of an anaphylactic reaction and older age. An egg OFC was associated with low risk of severe symptoms during OFC. Therefore, OFCs for patients with these risk factors should only be performed under specialist supervision with access to rapid treatment and full resuscitation equipment.

Japanese guidelines for food allergy 2017

Five years have passed since the Japanese Pediatric Guideline for Food Allergy (JPGFA) was first revised in 2011 from its original version. As many scientific papers related to food allergy have been published during the last 5 years, the second major revision of the JPGFA was carried out in 2016. In this guideline, food allergies are generally classified into four clinical types: (1) neonatal and infantile gastrointestinal allergy, (2) infantile atopic dermatitis associated with food allergy, (3) immediate-type of food allergy (urticaria, anaphylaxis, etc.), and (4) special forms of immediate-type of food allergy such as food-dependent exercise-induced anaphylaxis and oral allergy syndrome (OAS). Much of this guideline covers the immediate-type of food allergy that is seen during childhood to adolescence. Infantile atopic dermatitis associated with food allergy type is especially important as the onset of most food allergies occurs during infancy. We have discussed the neonatal and infantile gastrointestinal allergy and special forms of immediate type food allergy types separately. Diagnostic procedures are highlighted, such as probability curves and component-resolved diagnosis, including the recent advancement utilizing antigen-specific IgE. The oral food challenge using a stepwise approach is recommended to avoid complete elimination of causative foods. Although oral immunotherapy (OIT) has not been approved as a routine treatment by nationwide insurance, we included a chapter for OIT, focusing on efficacy and problems. Prevention of food allergy is currently the focus of interest, and many changes were made based on recent evidence. Finally, the contraindication between adrenaline and antipsychotic drugs in Japan was discussed among related medical societies, and we reached an agreement that the use of adrenaline can be allowed based on the physician's discretion. In conclusion, this guideline encourages physicians to follow the principle to let patients consume causative foods in any way and as early as possible.

Allergic reactions to milk appear sooner than reactions to hen's eggs: a retrospective study

BACKGROUND

Oral food challenge test doses are recommended to be performed at least 20 min apart; however, the times of symptom provocation from the start of the oral food challenge have never been compared between different foods. In this study, the durations from the start of the oral food challenge to symptom development in children with egg or milk allergy were compared.

METHODS

Thirty-eight and 74 children who had previously passed oral food challenges to 96 g of yogurt and pumpkin cake containing ¼ whole egg underwent oral food challenges with 200 mL raw cow's milk and 1 whole scrambled egg, respectively; of these, 15/38 and 33/74 children had a reaction.

RESULTS

The median ages of patients with a positive challenge were 5.8 and 5.1 years for milk and eggs, respectively. The median times for the first symptom occurrence were 20 min (range, 5-55 min) and 50 min (5-480 min), respectively (p = 0.009). The first symptoms developed within 30, 60, and 90 min in 12/15 (80 %), 15/15 (100 %), and 15/15 (100 %) children with milk allergies, and in 10/33 (30.3 %), 20/33 (60.6 %), and 26/33 (78.8 %) children with egg allergies, respectively. The median times of peak symptoms were 50 min (10-210 min) and 120 min (30-560 min) (p = 0.001), and those of symptom disappearance were 90 min (30-240 min) and 180 min (80-700 min) for milk and eggs (p = 0.002), respectively.

DISCUSSION

Based on the results of our study, symptoms developed within 30 min for only a subset of patients for eggs, and may even take upwards of 60 min to develop. The times of symptom disappearance were 90 min and 180 min for milk and eggs, respectively, indicating that egg-allergic patients should be observed for a longer period time than milk-allergic patients.

CONCLUSIONS

Allergic reactions induced by milk appeared and disappeared sooner than those induced by eggs.