Labial food challenge in children with food allergy

The current increase in the prevalence of food allergies appears to have several causes including better screening, improved diagnosis and changes in both the techniques used by food manufacturers and eating habits. Labial food challenge (LFC)is simple, rapid to perform and is associated with only low risks of systemic reaction. It is thus an appealing alternative to the oral food challenge (OFC) for pediatric use.
We report a series of 202 LFC performed over two years in 142 children with food allergy suspected from the case history, positive skin prick tests and specific serum IgE assays: 156 LFC were positive; and 46 negative, followed by positive single-blind, placebo-controlled food challenges (SB-PCFC). The foods provoking reactions were egg white (75 cases), peanut (60 cases), mustard (23 cases), cow's milk (13 cases), cod (8 cases), kiwi fruit, shrimp (4 cases each), chicken, peanut oil (3 cases each), hazel nuts (2 cases), and snails, apple, fennel, garlic, chilli peppers, pepper, and duck (1 case each). LFC positivity was mostly (89. 7% of cases) manifested as a labial edema with contiguous urticaria. There were systemic reactions in 4. 5% of cases: generalized urticaria, hoarseness and rapid-onset and generalized eczema. The 46 infants with negative LFC results had positive SBPCFC. The reactions were in 34 cases generalized urticaria, 10 cases asthma attacks, 2 cases early and generalized eczema, and in one case general anaphylactic shock. The sensitivity of the LFC was 77%. The LFC was easy to perform with children. Positive results indicate the presence of food allergy, but negative results require further investigations preferably double-blind, placebo-controlled food challenge (DBPCFC)     

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.     

Oral immunotherapy and tolerance induction in childhood

Prevalence rates of food allergy have increased rapidly in recent decades. Of concern, rates of increase are greatest among children under 5 yrs of age and for those food allergies that persist into adulthood such as peanut or tree nut allergy and shellfish allergy. Given these trends, the overall prevalence of food allergy will compound over time as the number of children affected by food allergy soars and a greater proportion of food‐allergic children are left with persistent disease into adulthood. It is therefore vital to identify novel curative treatment approaches for food allergy. Acquisition of oral tolerance to the diverse array of ingested food antigens and intestinal microbiota is an active immunologic process that is successfully established in the majority of individuals. In subjects who develop food allergy, there is a failure or loss of oral tolerance acquisition to a limited number of food allergens. Oral immunotherapy (OIT) offers a promising approach to induce specific oral tolerance to selected food allergens and represents a potential strategy for long‐term curative treatment of food allergy. This review will summarize the current understanding of oral tolerance and clinical trials of OIT for the treatment of food allergy.     

Addressing risk management difficulties in children with food allergies

Risk is a concept inherent in every medical procedure. It can be defined as the probability of an adverse event in a defined population over a specified period of time. In the frame of food allergy management, it might be related to a diagnostic procedure, a treatment, or the consumption of foods. The risk of an adverse event can also be augmented by individual factors. This rostrum article discusses various aspects faced by children with food allergies in the light of risk, and their practical implications. Identifying personal risks for severe reaction, such as unstable asthma, and correcting them whenever possible also contribute to a reduction of the risk inherent to food allergy. Among the facets discussed, oral food challenges (OFC) are the most common diagnostic procedures implying an inherent risk. The risk of OFCs can be minimized by correct indication and timing of the test, a safe setting, as well as by ensuring that the patient is otherwise well without potential stressor potentially increasing the risk of a more severe reaction. Oral immunotherapy (OIT) has been studied as a potential treatment for increasing the threshold dose for reaction, and thus reducing the risk of accidental reaction. Nevertheless, the procedure is not devoid of risk as the patients may and do often react during the course of the procedure. Ingestion of trace amounts in processed foods, mainly in community settings such as restaurants, schools, or day care, represents a potential risk of reactions, although for a minority of patients. Precautionary allergen labeling (PAL) is a widespread strategy to reduce the potential risk of reactions due to traces. However, PAL is currently inefficient due to inconsistent labeling, also not indicating a clear maximum amount possibly present in the manufactured food. Finally, cost-effectiveness needs to be considered in risk management, as many risk reduction procedures are clearly not cost-effective.     

Increasing specific immunoglobulin E levels correlate with the risk of anaphylaxis during an oral food challenge

Background

Oral food challenges (OFCs) are necessary to diagnose food allergies; however, these tests can cause anaphylaxis. Higher specific immunoglobulin E (sIgE) levels to causative food have been associated with a positive OFC. To date, no data have been found to indicate the factors associated with severe symptoms or anaphylaxis among challenge‐positive patients. This study aimed to clarify the association of sIgE with causative foods and anaphylaxis during OFC among the whole study population and challenge‐positive patients.

Methods

This cross‐sectional study collected symptom and severity data between June 2012 and December 2016 during an open OFC to diagnose food allergy or confirm tolerance acquisition. We analyzed the risk factors for anaphylaxis during OFC.

Results

A total of 2272 cases were analyzed (median age: 3.5 years; egg: 1166 cases; milk: 589 cases; wheat: 388 cases; and peanut: 129 cases). Among 979 challenge‐positive patients, anaphylactic reactions were observed in 334 cases. A statistically significant association was observed between anaphylaxis during OFC and higher sIgE levels to causative foods (odds ratio: 2.71, 95% confidence interval: 1.94‐3.78, for the third compared to the first tertile, P‐value for trend <.001). Only gastrointestinal, respiratory, cardiovascular, and neurological symptoms were also statistically significantly associated with higher sIgE levels to causative foods.

Conclusions

The risk of all symptoms, except skin symptoms, during OFCs increased with increasing sIgE levels, and this consequently increased anaphylaxis during OFCs. The mechanism of how sIgE affects the prevalence of gastrointestinal, respiratory, cardiovascular, and neurological symptoms or anaphylaxis is unknown; thus, further study is required.