Ana o 3 sIgE and diagnostic algorithms reduce cost of cashew allergy diagnosis in children compared with skin prick test: A cost comparison analysis.

BACKGROUND: In the absence of a clear clinical history of reaction, diagnosis of cashew allergy using skin prick tests (SPT) or cashew-specific IgE requires a high number of oral food challenges (OFC). By using Ana o 3 sIgE alone, or a two-step diagnostic algorithm using cashew sIgE followed by Ana o 3 sIgE, there is a reduced need for OFC. We aimed to perform a cost comparison for both of these approaches compared with cashew SPT alone. METHODS: Pooled individual-level data from 6 studies were used to determine diagnostic accuracy and OFC rate. Two studies used cashew SPT (n = 567, 198 allergic), with 95% positive and negative predictive values of ≥12 mm and <3 mm. Four studies were included in the pathways for Ana o 3 sIgE alone or a 2-step algorithm incorporating cashew and Ana o 3 sIgE (n = 271, 156 allergic). Cut-offs used were ≥8.5kUA/L and ≤0.1kUA/L for cashew sIgE and ≥0.35kUA/L and ≤0.1kUA/L for Ana o 3 sIgE. Costs were constructed based on unit prices from hospital inpatient admissions, expenses incurred by families, individual patient data on allergic reaction types and rates, and adrenaline autoinjector carriage, applying a health system perspective. RESULTS: Modeled data through the Ana o 3 pathway resulted in a 46.43% cost reduction (€307,406/1000 patients) compared with using cashew SPT alone (€573,854/1000 patients). The 2-step algorithm resulted in a 44.94% cost reduction compared with SPT alone (€315,952.82/1000 patients). Both the Ana o 3 pathway and 2-step algorithm resulted in a 79%-80% reduction in OFCs compared with SPT. CONCLUSIONS: Using Ana o 3 as a standalone test for cashew allergy diagnosis or a 2-step algorithm incorporating cashew sIgE and Ana o 3 sIgE is accurate and results in a large reduction in both OFCs and health system costs compared with cashew SPT alone.

A systematic assessment of structural heterogeneity and IgG/IgE-binding of ovalbumin.

Ovalbumin (OVA), one of the major allergens in hen egg, exhibits extensive structural heterogeneity due to a range of post-translational modifications (PTMs). However, analyzing the structural heterogeneity of native OVA is challenging, and the relationship between heterogeneity and IgG/IgE-binding of OVA remains unclear. In this work, ion exchange chromatography (IXC) with salt gradient elution and on-line detection by native electrospray ionization mass spectrometry (ESI MS) was used to assess the structural heterogeneity of OVA, while inhibition-ELISA was used to assess the IgG/IgE binding characteristics of OVA. Over 130 different OVA proteoforms (including glycan-free species and 32 pairs of isobaric species) were identified. Proteoforms with acetylation, phosphorylation, oxidation and succinimide modifications had reduced IgG/IgE binding capacities, whereas those with few structural modifications had higher IgG/IgE binding capacities. OVA isoforms with a sialic acid-containing glycan modification had the highest IgG/IgE binding capacity. Our results demonstrate that on-line native IXC/MS with salt gradient elution can be used for rapid assessment of the structural heterogeneity of proteins. An improved understanding of the relationship between IgG/IgE binding capacity and OVA structure provides a basis for developing biotechnology or food processing methods for reducing protein allergenicity reduction.

Milk allergy most burdensome in multi-food allergic children.

BACKGROUND: Food allergy is a substantial health burden, which disproportionately affects children. Among children with food allergy, as many as 70% have multiple food allergies. Whereas the overall burden of food allergy on quality of life has been described, little is known about the burden of individual allergens. We aimed to examine the perception of burden among families with multiple food-allergic children. METHODS: Parents of children with 1 + children with multiple food allergies including milk responded to online questions, including both open-ended and closed-ended questions on food allergy-related burdens of time, financial costs, social restrictions, and emotional demands. RESULTS: Overall, 64 children (69.8% boys) of whom (73.0%) most were aged 10 and younger were included. Most had been diagnosed with food allergy in infancy and by a (pediatric) allergist. Other common allergies included peanut (65.6%), tree nuts (57.8%), egg (76.6%), and sesame (31.3%). Quantitatively, milk allergy was reported as carrying the most burden, including most socially limiting (81.5%), requiring the most planning (75.9%), causing the most anxiety (68.5%), most challenging to find "safe" or allergy-friendly foods (72.2%), and costly (81.5%). Qualitatively, we identified five themes that captured burdens associated with costs, marketing of milk products to children, risk of cross-contamination, ubiquity of milk/dairy and public confusion with lactose intolerance, and an unwillingness of others to accommodate the allergy. CONCLUSION: Parents whose children have multiple food allergies, including milk, report milk as the allergy associated with the greatest time, financial, social, and emotional burdens.

An assessment of the impact of extraction and digestion protocols on multiplexed targeted protein quantification by mass spectrometry for egg and milk allergens.

The unintentional presence of even trace amounts of certain foods constitutes a major hazard for those who suffer from food allergies. For many food industries, product and raw ingredient surveillance forms part of their risk assessment procedures. This may require the detection of multiple allergens in a wide variety of matrices. Mass spectrometry offers a possible solution for the quantification of multiple allergens in a single analysis. The capability of MS to quantify many peptides from a complex protein digestion is well known. However, a lack of matrix certified reference materials has made the optimisation of extraction and digestion conditions for multiplexed allergen quantification difficult to assess. Here, we report a systematic study, using preliminary screening followed by a Design of Experiments approach, to find the optimal buffer and digestion conditions for detecting milk and egg protein markers in a model processed food matrix. Five of the most commonly used buffers, two chaotropic reagents and two reducing reagents were assessed for the optimal extraction of multiple protein markers. While the choice of background buffer had little impact, the use of chaotropic and reducing reagents showed significant benefits for the extraction of most proteins. A full factorial design experiment was applied to the parameters shown to have a significant impact on protein recovery. These studies suggest that a single optimal set of extraction conditions enabling the quantitative recovery of all proteins is not easily achieved. Therefore, although MS is capable of the simultaneous quantification of many peptides in a single run, greater consideration of protein extraction is required before these are applied for multiplex allergen quantification in food matrices. Graphical abstract.

The health and economic outcomes of early egg introduction strategies.

BACKGROUND: Studies suggest early egg introduction (EEI) in the first year of life is associated with reduced risk of developing egg allergy. No US recommendations exist regarding optimally implementing EEI. METHODS: Using simulation and Markov modelling over a 20-year horizon, we explored optimal EEI strategies applied to US, European and Canadian populations, comparing screening of high-risk infants (skin prick testing [SPT] or serum-specific IgE[sIgE]) before introducing cooked egg at 6 months of life vs egg introduction at home, without screening, for all infants. RESULTS: A no-screen approach dominated egg SPT screening of high-risk infants with early-onset eczema. Base model per-patient incremental costs of SPT were $6865 US dollars (USD), 6801 euros and $10 610 Canadian dollars (CAD). For egg sIgE screening in primary care settings, base model incremental costs were $16 722 USD, 18 072 euros and $28 193 CAD. As the simulation concluded 2.5% were egg allergic without screening vs 9.5%, 12% and 21.4% of children undergoing SPT, delayed introduction or sIgE screening. Incremental societal costs from screening reached $2 009 351 175 USD for SPT and $4 894 445 790 USD for sIgE testing. In sensitivity analyses, if the risk of reaction with initial egg ingestion was ≥22.5%, SPT before EEI became a preferred strategy. A no-screen approach dominated both EEI of raw pasteurized egg and delayed cooked egg introduction approaches. CONCLUSIONS: Assuming initial reaction rates < 22.5%, a no-screening EEI cooked egg approach has superior health and economic benefits in terms of number of egg allergy cases prevented and total healthcare costs vs screening testing.

Assessment of the Allergenic Potential of the Main Egg White Proteins in BALB/c Mice.

This work aimed to assess the contribution of the major egg white proteins, ovalbumin, ovomucoid, and lysozyme, to the induction and elicitation of allergenic responses. For this purpose, BALB/c mice were orally administered either the individual egg allergens or a mixture of the three proteins in the same proportion, to evaluate their relative allergenicity avoiding their different abundance in egg white. Cholera toxin was used as a T helper 2 (Th2)-polarizing adjuvant. Ovomucoid and lysozyme triggered the most severe anaphylaxis reactions upon oral challenge. In comparison to ovalbumin and ovomucoid, lysozyme was a more active promotor of early immunoglobulin E and immunoglobulin G1 production and stimulated stronger Th2-biased responses from both mesenteric lymph node and spleen cells. These results indicate that lysozyme is highly immunogenic and should be considered as a major allergen, whose clinical usefulness in the diagnosis, prognosis, and therapeutic approaches of egg allergy deserves further consideration.

"To screen or not to screen": Comparing the health and economic benefits of early peanut introduction strategies in five countries.

BACKGROUND: Early peanut introduction (EPI) in the first year of life is associated with reduced risk of developing peanut allergy in children with either severe eczema and/or egg allergy. However, EPI recommendations differ among countries with formal guidelines. METHODS: Using simulation and Markov modeling over a 20-year horizon to attempt to explore optimal EPI strategies applied to the US population, we compared high-risk infant-specific IgE peanut screening (US/Canadian) with the Australiasian Society for Clinical Immunology and Allergy (Australia/New Zealand) (ASCIA) and the United Kingdom Department of Health (UKDOH)-published EPI approaches. RESULTS: Screening peanut skin testing of all children with early-onset eczema and/or egg allergy before in-office peanut introduction was dominated by a no screening approach, in terms of number of cases of peanut allergy prevented, quality-adjusted life years (QALY), and healthcare costs, although screening resulted in a slightly lower rate of allergic reactions to peanut per patient in high-risk children. Considering costs of peanut allergy in high-risk children, the per-patient cost of early introduction without screening over the model horizon was $6556.69 (95%CI, $6512.76-$6600.62), compared with a cost of $7576.32 (95%CI, $7531.38-$7621.26) for skin test screening prior to introduction. From a US societal perspective, screening prior to introduction cost $654 115 322 and resulted in 3208 additional peanut allergy diagnoses. Both screening and nonscreening approaches dominated deliberately delayed peanut introduction. CONCLUSIONS: A no-screening approach for EPI has superior health and economic benefits in terms of number of peanut allergy cases prevented, QALY, and total healthcare costs compared to screening and in-office peanut introduction.

Subjective Well-Being Is Associated with Food Behavior and Demographic Factors in Chronically Ill Older Japanese People Living Alone.

OBJECTIVES: This study aimed to examine the relationships among subjective well-being, food and health behaviors, socioeconomic factors, and geography in chronically ill older Japanese adults living alone. DESIGN: The design was a cross-sectional, multilevel survey. A questionnaire was distributed by post and self-completed by participants. SETTING: The sample was drawn from seven towns and cities across Japan. PARTICIPANTS: A geographic information system was used to select a representative sample of older people living alone based on their proximity to a supermarket. Study recruitment was conducted with municipal assistance. MEASUREMENTS: To assess subjective well-being and food and health behaviors of respondents with disease, a logistic regression analysis was performed using stepwise variable analyses, adjusted for respondent age, socioeconomic status, and proximity to a supermarket. The dependent variable was good or poor subjective well-being. RESULTS: In total, 2,165 older people (744 men, 1,421 women) completed the questionnaire (63.5% response rate). Data from 737 men and 1,414 women were used in this study. Among people with a chronic disease, individuals with good subjective well-being had significantly higher rates than those with poor subjective well-being for satisfaction with meal quality and chewing ability, food diversity, food intake frequency, perception of shopping ease, having someone to help with food shopping, eating home-produced vegetables, preparing breakfast themselves, eating with other people, and high alcohol consumption. A stepwise logistic analysis showed that the factors strongly related to poor subjective well-being were shopping difficulty (men: odds ratio [OR] = 3.19, 95% confidence interval [CI], 1.94-5.23; P < 0.0001; women: OR = 2.20, 95% CI, 1.54-3.14; P < 0.0001), not having someone to help with food shopping (women: OR = 1.41, 95% CI, 1.01-1.97; P = 0.043), not preparing breakfast (women: OR = 2.36, 95% CI, 1.40-3.98; P = 0.001), and eating together less often (women: OR = 1.99, 95% CI, 1.32-3.00; P = 0.002). CONCLUSION: Subjective well-being of people with chronic diseases is associated with food intake and food behavior. The factors that affect poor subjective well-being in chronically ill older Japanese people living alone include food accessibility and social communication.

Assessment of IgE Reactivity of ß-Casein by Western Blotting After Digestion with Simulated Gastric Fluid.

Cow's milk allergy is defined as an immunologically mediated adverse reaction to cow's milk proteins and it is usually, along with hen's egg allergy, the first food allergy identified in childhood.One of the main aspects to consider when evaluating the allergenic potential of food proteins is the effect of gastric digestion. It is known that allergens are usually able to survive the harsh acidic environment of the stomach, tolerate the presence of surfactants, and resist digestion by pepsin. They might also be digested into high molecular weight peptide fragments, which retain the same, or sometimes increased, IgE-binding. In this respect, western blotting is a highly sensitive and efficient technique that we have used to detect IgE-binding to the digests of milk and egg proteins. Given the importance of the resistance of food proteins to gastric digestion in their capacity to modulate the immune response, we describe in this chapter the assessment of IgE reactivity of a relevant cow's milk allergen, ß-casein, by western blotting after simulated digestion under relevant physiological conditions.

The economic effect and outcome of delaying oral food challenges.

BACKGROUND: Food specific IgE (sIgE) is a useful marker to assess predictability of oral food challenge (OFC) outcome. A threshold of less than 2 kUA/L for peanut, egg, and milk has been proposed as a 50% negative predictive value at which patients may pass an OFC. OBJECTIVE: To assess the economic effect and outcome of delaying OFCs. METHODS: A retrospective analysis was performed for peanut, egg, and milk OFCs conducted between 2001 and 2012 at a tertiary food allergy referral center. Delayed OFC was defined as greater than 12 months from the time the sIgE level became less than 2 kUA/L. Time to OFC was explored in association with skin prick test result (wheal size), OFC outcome, and the economic effect of delay. RESULTS: Of 319 challenges, 173 OFCs were delayed (54.2%) by a mean time of 35.5 months (range, 13-123 months) vs a mean time of 4.2 months in the 146 challenges that were not delayed (P < .001). The overall OFC passage rate was 89.9%. There was no association between delayed OFC and history of anaphylaxis, type of allergen, age at OFC, or challenge outcome. Delay in OFC was associated with an estimated mean economic cost of $12,203 per patient ($4,184 per 12 months) and $1,951,487 total (total delay, 5,597 months) in this population. CONCLUSION: Despite a 50% negative predictive value, more than 50% of OFCs were delayed in this population by a mean time of nearly 3 years. Delaying OFC is associated with increased costs, and quality improvement is needed to help decrease time to OFC and reduce the economic burden of food allergy on families and the health care system.

Assessment of Allergy to Milk, Egg, Cod, and Wheat in Swedish Schoolchildren: A Population Based Cohort Study.

OBJECTIVES: Knowledge about the prevalence of allergies to foods in childhood and adolescence is incomplete. The purpose of this study was to investigate the prevalence of allergies to milk, egg, cod, and wheat using reported data, clinical examinations, and double-blind placebo-controlled food challenges, and to describe the phenotypes of reported food hypersensitivity in a cohort of Swedish schoolchildren. METHODS: In a population-based cohort of 12-year-old children, the parents of 2612 (96% of invited) completed a questionnaire. Specific IgE antibodies to foods were analyzed in a random sample (n=695). Children reporting complete avoidance of milk, egg, cod, or wheat due to perceived hypersensitivity and without physician-diagnosed celiac disease were invited to undergo clinical examination that included specific IgE testing, a celiac screening test, and categorization into phenotypes of food hypersensitivity according to preset criteria. Children with possible food allergy were further evaluated with double-blind challenges. RESULTS: In this cohort, the prevalence of reported food allergy to milk, egg, cod, or wheat was 4.8%. Food allergy was diagnosed in 1.4% of the children after clinical evaluation and in 0.6% following double-blind placebo-controlled food challenge. After clinical examination, children who completely avoided one or more essential foods due to perceived food hypersensitivity were categorized with the following phenotypes: allergy (29%), outgrown allergy (19%), lactose intolerance (40%), and unclear (12%). CONCLUSIONS: There was a high discrepancy in the prevalence of allergy to milk, egg, cod and wheat as assessed by reported data, clinical evaluation, and double-blind food challenges. Food hypersensitivity phenotyping according to preset criteria was helpful for identifying children with food allergy.

Influence of early-life exposures on food sensitization and food allergy in an inner-city birth cohort.

OBJECTIVE: Previous data suggest that food allergy (FA) might be more common in inner-city children; however, these studies have not collected data on both sensitization and clinical reactivity or early-life exposures. METHODS: Children in the Urban Environment and Childhood Asthma birth cohort were followed through age 5 years. Household exposures, diet, clinical history, and physical examinations were assessed yearly; levels of specific IgE to milk, egg, and peanut were measured at 1, 2, 3, and 5 years of age. On the basis of sensitization (IgE ≥0.35 kU/L) and clinical history over the 5-year period, children were classified as having FA or being possibly allergic, sensitized but tolerant, or not allergic/not sensitized. RESULTS: Five hundred sixteen children were included. Overall, 55.4% were sensitized (milk, 46.7%; egg, 31.0%; and peanut, 20.9%), whereas 9.9% were categorized as having FA (peanut, 6.0%; egg, 4.3%; and milk, 2.7%; 2.5% to >1 food). The remaining children were categorized as possibly allergic (17.0%), sensitized but tolerant (28.5%), and not sensitized (44.6%). Eighteen (3.5%) reported reactions to foods for which IgE levels were not measured. Food-specific IgE levels were similar in children with FA versus sensitized but tolerant children, except for egg, levels of which were higher in patients with FA at ages 1 and 2 years. FA was associated with recurrent wheeze, eczema, aeroallergen sensitization, male sex, breast-feeding, and lower endotoxin exposure in year 1 but not with race/ethnicity, income, tobacco exposure, maternal stress, or early introduction of solid foods. CONCLUSIONS: Even given that this was designed to be a high-risk cohort, the cumulative incidence of FA is extremely high, especially considering the strict definition of FA that was applied and that only 3 common allergens were included.

A Bayesian hierarchical model for identifying epitopes in peptide microarray data.

Peptide Microarray Immunoassay (PMI for brevity) is a novel technology that enables researchers to map a large number of proteomic measurements at a peptide level, providing information regarding the relationship between antibody response and clinical sensitivity. PMI studies aim at recognizing antigen-specific antibodies from serum samples and at detecting epitope regions of the protein antigen. PMI data present new challenges for statistical analysis mainly due to the structural dependence among peptides. A PMI is made of a complete library of consecutive peptides. They are synthesized by systematically shifting a window of a fixed number of amino acids through the finite sequence of amino acids of the antigen protein as ordered in the primary structure of the protein. This implies that consecutive peptides have a certain number of amino acids in common and hence are structurally dependent. We propose a new flexible Bayesian hierarchical model framework, which allows one to detect recognized peptides and bound epitope regions in a single framework, taking into account the structural dependence between peptides through a suitable latent Markov structure. The proposed model is illustrated using PMI data from a recent study about egg allergy. A simulation study shows that the proposed model is more powerful and robust in terms of epitope detection than simpler models overlooking some of the dependence structure.

Allergy assessment in children with eosinophilic esophagitis.

BACKGROUND: Eosinophilic esophagitis (EoE) is of growing interest for pediatricians and allergists. There is no general agreement about diagnostic and clinical management procedures. The objective of this prospective, observational study was to evaluate the efficacy of a protocol for the etiologic diagnosis and accurate treatment of EoE in the pediatric population. PATIENTS AND METHODS: Starting in 2001, patients aged 0 to 14 years with a diagnosis of EoE were consecutively included in a protocol which included an allergy study. Depending on the results, an avoidance or elemental diet was established. Topical corticosteroids were prescribed to patients who rejected the diet. Clinical, endoscopic, and histological evaluation was performed to assess response. In the case of disease remission, challenge tests were performed to identify the offending food. RESULTS: Seventeen patients were included. Most of them were male (14/17) and a high percentage (88%) had a history of allergy as well as a history of atopy in parents. Fifteen patients were sensitized to 1 or more foods. With this protocol and the subsequent treatment, 9 out of 17 patients were cured (1 out of 4 with swallowed corticosteroids, 3 out of 3 with an elemental diet, and 5 out of 12 with an avoidance diet). The offending food was identified in 8117 patients. Milk and eggs were the most common foods implicated. CONCLUSIONS: The allergy study was a useful diagnostic tool but it was not sufficient to identify the offending food.An elemental diet should be attempted before food is excluded as the cause of the disease.

Differences in allergenic potential of food extracts following oral exposure in mice reflect differences in digestibility: potential approaches to safety assessment.

An animal model for food allergy is needed to assess genetically modified food crops for potential allergenicity. The ideal model must produce allergic antibody (IgE) to proteins differentially according to known allergenicity before being used to accurately identify potential allergens among novel proteins. The oral route is the most relevant for exposure to food antigens, and a protein's stability to digestion is a current risk assessment tool based on this natural route. However, normal laboratory animals do not mount allergic responses to proteins administered orally due to oral tolerance, an immunologic mechanism which specifically suppresses IgE. To circumvent oral tolerance and evoke differential IgE responses to a panel of allergenic and nonallergenic food extracts, female C3H/HeJ mice were exposed subcutaneously or orally with cholera toxin as an adjuvant. All foods elicited IgE by the subcutaneous route. Oral exposure, however, resulted in IgE to allergens (peanut, Brazil nut, and egg white) but not to nonallergens (spinach and turkey), provided that the dose and exposures were limited. Additionally, in vitro digestibility assays demonstrated the presence of digestion-stable proteins in the allergenic food extracts but not in the nonallergenic foods. Our results suggest that the subcutaneous route is inadequate to distinguish allergens from nonallergens, but oral exposure under the appropriate experimental conditions will result in differential allergic responses in accordance with known allergenicity. Moreover, those foods containing digestion-resistant proteins provoke allergic responses in this model, supporting the current use of pepsin resistance in the decision tree for potential allergenicity assessment.