Deriving individual threshold doses from clinical food challenge data for population risk assessment of food allergens.

BACKGROUND: Food allergies are a significant public health issue, and the only effective management option currently available is strict avoidance of all foods containing the allergen. In view of the practical impossibility of limiting risks to zero, quantitative allergen risk assessment and management strategies are needed. OBJECTIVE: We sought to develop appropriate methods for informing population-based risk assessments and risk management programs to benefit all stakeholders but particularly patients with food allergy. METHODS: Individual thresholds for food allergens (maximum tolerable doses and minimum eliciting doses) can ideally be established through double-blind, placebo-controlled food challenges. If double-blind, placebo-controlled food challenge data are not available, data from widely used open food challenges using predefined objective criteria can also provide useful data regarding minimum eliciting doses. For more than 20 years, the Netherlands Organisation for Applied Scientific Research and the Food Allergy Research and Resource Program at the University of Nebraska-Lincoln have been collecting individual maximum tolerable doses and minimum eliciting doses that produce objective symptoms from published and unpublished clinical data to better refine knowledge regarding the sensitivity of the population to food allergens. RESULTS: In this article we provide in-depth insights into the methodology applied by the Netherlands Organisation for Applied Scientific Research and Food Allergy Research and Resource Program to derive individual maximum tolerable doses and minimum eliciting doses for objective symptoms from clinical food challenge data. More than 90 examples for determining individual allergic thresholds are presented. CONCLUSION: With the methodology presented in this article, we aim to stimulate harmonization and transparency in quantitative food allergen risk assessment and risk management programs, encouraging their wider adoption.

IgE Cross-Reactivity of Cashew Nut Allergens.

BACKGROUND: Allergic sensitisation towards cashew nut often happens without a clear history of eating cashew nut. IgE cross-reactivity between cashew and pistachio nut is well described; however, the ability of cashew nut-specific IgE to cross-react to common tree nut species and other Anacardiaceae, like mango, pink peppercorn, or sumac is largely unknown. OBJECTIVES: Cashew nut allergic individuals may cross-react to foods that are phylogenetically related to cashew. We aimed to determine IgE cross-sensitisation and cross-reactivity profiles in cashew nut-sensitised subjects, towards botanically related proteins of other Anacardiaceae family members and related tree nut species. METHOD: Sera from children with a suspected cashew nut allergy (n = 56) were assessed for IgE sensitisation to common tree nuts, mango, pink peppercorn, and sumac using dot blot technique. Allergen cross-reactivity patterns between Anacardiaceae species were subsequently examined by SDS-PAGE and immunoblot inhibition, and IgE-reactive allergens were identified by LC-MS/MS. RESULTS: From the 56 subjects analysed, 36 were positive on dot blot for cashew nut (63%). Of these, 50% were mono-sensitised to cashew nuts, 19% were co-sensitised to Anacardiaceae species, and 31% were co-sensitised to tree nuts. Subjects co-sensitised to Anacardiaceae species displayed a different allergen recognition pattern than subjects sensitised to common tree nuts. In pink peppercorn, putative albumin- and legumin-type seed storage proteins were found to cross-react with serum of cashew nut-sensitised subjects in vitro. In addition, a putative luminal binding protein was identified, which, among others, may be involved in cross-reactivity between several Anacardiaceae species. CONCLUSIONS: Results demonstrate the in vitro presence of IgE cross-sensitisation in children towards multiple Anacardiaceae species. In this study, putative novel allergens were identified in cashew, pistachio, and pink peppercorn, which may pose factors that underlie the observed cross-sensitivity to these species. The clinical relevance of this widespread cross-sensitisation is unknown.

Development and construct validation of a parent-proxy quality of life instrument in children with bronchopulmonary dysplasia aged 4-8 years old.

PURPOSE: Children with bronchopulmonary dysplasia often develop complications that affect them well into adult life. Very little is known about how this affects their quality of life, since no sensitive instrument is available to measure health-related quality of life in this population. In this study, a Dutch parent-proxy instrument was developed for this purpose. METHODS: A list of items was generated after literature search and interviews with both parents of patients and clinical experts. Clinically relevant items were selected with the clinical impact method and item analysis. Results of clinical tests to measure complications in children with bronchopulmonary dysplasia were correlated with these items to select the items that show construct validity. Cronbach's alpha was calculated to estimate internal consistency of the items in the final questionnaire. RESULTS: In total, 92 children and their parents and 7 clinicians participated. Of 130 identified items, 47 showed clinical relevance. Spirometry, the Child Behavior Checklist, mean arterial pressure, and body mass index were used to determine construct validity of 33 items. These items were structured within five domains: pulmonary complaints, school functioning, growth and nutrition, exercise and locomotion, emotional functioning and health care concerns. The questionnaire showed excellent internal consistency with Cronbach's alpha of 0.919. CONCLUSION: This study developed a disease-specific parent-proxy instrument to measure health-related quality of life in children with bronchopulmonary dysplasia aged 4-8 years old, the BPD-QoL. All included items show construct validity and internal consistency reliability. Future research should focus on further validation and analysis of responsiveness and reliability.

Genome-wide association study and meta-analysis in multiple populations identifies new loci for peanut allergy and establishes C11orf30/EMSY as a genetic risk factor for food allergy.

BACKGROUND: Peanut allergy (PA) is a complex disease with both environmental and genetic risk factors. Previously, PA loci were identified in filaggrin (FLG) and HLA in candidate gene studies, and loci in HLA were identified in a genome-wide association study and meta-analysis. OBJECTIVE: We sought to investigate genetic susceptibility to PA. METHODS: Eight hundred fifty cases and 926 hyper-control subjects and more than 7.8 million genotyped and imputed single nucleotide polymorphisms (SNPs) were analyzed in a genome-wide association study to identify susceptibility variants for PA in the Canadian population. A meta-analysis of 2 phenotypes (PA and food allergy) was conducted by using 7 studies from the Canadian, American (n = 2), Australian, German, and Dutch (n = 2) populations. RESULTS: An SNP near integrin α6 (ITGA6) reached genome-wide significance with PA (P = 1.80 × 10-8), whereas SNPs associated with Src kinase-associated phosphoprotein 1 (SKAP1), matrix metallopeptidase 12 (MMP12)/MMP13, catenin α3 (CTNNA3), rho GTPase-activating protein 24 (ARHGAP24), angiopoietin 4 (ANGPT4), chromosome 11 open reading frame (C11orf30/EMSY), and exocyst complex component 4 (EXOC4) reached a threshold suggestive of association (P ≤ 1.49 × 10-6). In the meta-analysis of PA, loci in or near ITGA6, ANGPT4, MMP12/MMP13, C11orf30, and EXOC4 were significant (P ≤ 1.49 × 10-6). When a phenotype of any food allergy was used for meta-analysis, the C11orf30 locus reached genome-wide significance (P = 7.50 × 10-11), whereas SNPs associated with ITGA6, ANGPT4, MMP12/MMP13, and EXOC4 and additional C11orf30 SNPs were suggestive (P ≤ 1.49 × 10-6). Functional annotation indicated that SKAP1 regulates expression of CBX1, which colocalizes with the EMSY protein coded by C11orf30. CONCLUSION: This study identifies multiple novel loci as risk factors for PA and food allergy and establishes C11orf30 as a risk locus for both PA and food allergy. Multiple genes (C11orf30/EMSY, SKAP1, and CTNNA3) identified by this study are involved in epigenetic regulation of gene expression.

Small percentage of anaphylactic reactions treated with epinephrine during food challenges in Dutch children.

BACKGROUND: Severe allergic reactions, including anaphylaxis, occur during oral food challenges (OFCs) and the first-line treatment of anaphylaxis is epinephrine. OBJECTIVE: To evaluate the percentage of anaphylactic reactions treated with epinephrine during OFCs and to identify associated factors for the administration of epinephrine. METHODS: Children who underwent an OFC with peanut, hazelnut, cow's milk, hen's egg, or cashew nut from 2005 through 2015 in the Netherlands were evaluated. Children with reactions meeting the criteria for anaphylaxis according to the European Academy of Allergy and Clinical Immunology guidelines for food allergy and anaphylaxis were included. Children with an anaphylactic reaction treated with vs without epinephrine were compared. Possible factors associated with the administration of epinephrine, such as age, sex, symptoms consistent with asthma, history of an allergic reaction to the tested allergen, and symptom types during the anaphylactic reaction, were evaluated using logistic regression analysis. RESULTS: Eighty-three children in clinical and research settings (43% boys; median age, 7 years; range, 1-17) who met the criteria for anaphylaxis were included in this study. Thirty-two of 83 children (39%) with anaphylaxis were treated with epinephrine. Respiratory symptoms during the OFC were treated significantly more often with epinephrine than gastrointestinal symptoms (P = .01). CONCLUSION: Only 39% of children with anaphylaxis, according to the guideline criteria, were treated with epinephrine during the OFC and most of these children had respiratory symptoms. There is need for an easy-to-use international guideline for the treatment of allergic symptoms during OFCs.

Association of food allergy and atopic dermatitis exacerbations.

BACKGROUND: Atopic dermatitis (AD) and food allergy frequently coexist in children. OBJECTIVE: To examine the association between food allergy and AD. METHODS: Between 2001 and 2011, children referred to our tertiary care center underwent double-blind, placebo-controlled food challenges (DBPCFCs) for one or more suspected food allergies as part of regular care. Immediate reactions were observed and recorded by allergy nursing staff, whereas late reactions were ascertained by semistructured telephone interview 48 hours after challenge. To test to which degree specific IgE results were predictive in the outcome of DBPCFCs in children with and without (previous and current) AD, logistic regression analysis was performed. RESULTS: A total of 1186 DBPCFCs were studied. Sensitization to foods occurred significantly more often in children with previous AD. The association between specific IgE results and the outcome of DBPCFCs was significant for children with and without (previous and current) AD but stronger for children without current AD. The positivity rate of DBPCFCs in children with mild, moderate, and severe AD was 53.3%, 51.7%, and 100%, respectively. Children with AD and a history of worsening AD as their only symptom reacted as often to placebo as to challenge food. CONCLUSION: Children with current AD are more frequently asymptomatically sensitized to the foods in question than those without AD. In addition, children suspected of food allergy should be considered for testing, regardless of the severity of their AD. Our results suggest that children with exacerbation of AD in the absence of other allergic symptoms are unlikely to be food allergic.

Consensus Communication on Early Peanut Introduction and Prevention of Peanut Allergy in High-Risk Infants.

The purpose of this brief communication is to highlight emerging evidence regarding potential benefits of supporting early rather than delayed peanut introduction during the period of complementary food introduction in infants. This document should be considered as interim guidance based on consensus among the following organizations: American Academy of Allergy, Asthma, and Immunology, American Academy of Pediatrics, American College of Allergy, Asthma, and Immunology, Australasian Society of Clinical Immunology and Allergy, Canadian Society of Allergy and Clinical Immunology, European Academy of Allergy and Clinical Immunology, Israel Association of Allergy and Clinical Immunology, Japanese Society for Allergology, Society for Pediatric Dermatology, and World Allergy Organization. More formal guidelines regarding early-life, complementary feeding practices and the risk of allergy development will follow in the next year from the National Institute of Allergy and Infectious Diseases-sponsored Working Group and the European Academy of Allergy and Clinical Immunology.

Consensus communication on early peanut introduction and the prevention of peanut allergy in high-risk infants.

The purpose of this brief communication is to highlight emerging evidence to existing guidelines regarding potential benefits of supporting early, rather than delayed, peanut introduction during the period of complementary food introduction in infants. This document should be considered as interim guidance based on consensus among the following organizations: American Academy of Allergy, Asthma & Immunology, American Academy of Pediatrics, American College of Allergy, Asthma & Immunology, Australasian Society of Clinical Immunology and Allergy, Canadian Society of Allergy and Clinical Immunology, European Academy of Allergy and Clinical Immunology, Israel Association of Allergy and Clinical Immunology, Japanese Society for Allergology, Society for Pediatric Dermatology, and World Allergy Organization. More formal guidelines regarding early-life, complementary feeding practices and the risk of allergy development will follow in the next year from the National Institute of Allergy and Infectious Diseases-sponsored Working Group and the European Academy of Allergy and Clinical Immunology.

Consensus communication on early peanut introduction and the prevention of peanut allergy in high-risk infants.

The purpose of this brief communication is to highlight emerging evidence to existing guidelines regarding potential benefits of supporting early, rather than delayed, peanut introduction during the period of complementary food introduction in infants. This document should be considered as interim guidance based on consensus among the following organizations: American Academy of Allergy, Asthma & Immunology, American Academy of Pediatrics, American College of Allergy, Asthma & Immunology, Australasian Society of Clinical Immunology and Allergy, Canadian Society of Allergy and Clinical Immunology, European Academy of Allergy and Clinical Immunology, Israel Association of Allergy and Clinical Immunology, Japanese Society for Allergology, Society for Pediatric Dermatology, and World Allergy Organization. More formal guidelines regarding early-life, complementary feeding practices and the risk of allergy development will follow in the next year from the National Institute of Allergy and Infectious Diseases-sponsored Working Group and the European Academy of Allergy and Clinical Immunology.

Health-related quality of life in food-allergic adults from eight European countries.

BACKGROUND: Food allergy can impair health-related quality of life (HRQL). Food Allergy Quality of Life Questionnaires (FAQLQs) have been developed and validated, including an adult form (FAQLQ-AF). HRQL has not, to date, been measured across different European countries using a uniform methodology. OBJECTIVE: To translate and validate the FAQLQ-AF for use in 8 European countries (Iceland, The Netherlands, Poland, France, Spain, Italy, Greece, and Sweden). METHODS: The English FAQLQ-AF was translated, back-translated, and compared for use in the 8 relevant European languages. Adults with a perceived food allergy were recruited from outpatient departments and through a community survey. Participants completed the FAQLQ-AF, the Food Allergy Independent Measure, and questions concerning participants' characteristics. Validity of the FAQLQ-AF was analyzed for use in the 8 countries. RESULTS: The FAQLQ-AF had strong construct validity (r > 0.59) and an excellent internal consistency (Cronbach α > 0.95) in all countries. Total FAQLQ-AF scores (range 3.2-5.0) were significantly different across participating countries. CONCLUSION: The FAQLQ-AF is a suitable and valid instrument for measuring HRQL in food-allergic adults in Iceland, The Netherlands, Poland, France, Spain, Italy, Greece, and Sweden. The impact of food allergy on HRQL seems to differ among adults from the 8 participating European countries.

Threshold dose distributions for 5 major allergenic foods in children.

BACKGROUND: For most allergenic foods, insufficient threshold dose information within the population restricts the advice on levels of unintended allergenic foods which should trigger precautionary labeling on prepackaged foods. OBJECTIVE: We wanted to derive threshold dose distributions for major allergenic foods and to elaborate the protein doses at which a proportion of the allergic population is likely to respond. METHODS: For 7 allergenic foods double-blind, placebo-controlled food challenges (DBPCFCs) with a positive outcome for allergic reactions were selected from the clinical database of children routinely tested to diagnose food allergy at the University Medical Center Groningen. For each allergen 2 population threshold distributions were determined with the individual minimal eliciting dose and the preceding dose of each DBPCFC for objective symptoms and any symptom (either subjective or objective). RESULTS: Individual positive DBPCFCs were available for peanut (n = 135), cow's milk (n = 93), hen's egg (n = 53), hazelnut (n = 28), and cashew nut (n = 31). Fewer children were challenged with soy (n = 10) or walnut (n = 13). Threshold dose distributions showed a good statistical and visual fit. The protein dose at which 5% of the allergic population is likely to respond with objective reactions was 1.6 mg for peanut, 1.1 mg for cow's milk, 1.5 mg for hen's egg, 7.4 mg for cashew nut, and 0.29 mg for hazelnut. Thresholds for any symptom were on average 2 to 6 times lower than for objective symptoms. The 95% upper and lower confidence intervals of the threshold distributions were overlapping. The peanut threshold distribution on objective symptoms was similar to the distribution of another European center. CONCLUSIONS: Threshold distribution curves and eliciting doses are a powerful tool to compare different allergenic foods and for informing policy on precautionary labeling.

Quality of life is more impaired in patients seeking medical care for food allergy.

BACKGROUND: Food allergy (FA) affects 2-4% of adults, but only a small percentage visit an outpatient clinic for a thorough evaluation. METHODS: A matched case-control study was used to compare health-related quality of life (HRQL) of the Dutch general population that did not seek medical care for their FA with outpatients who did seek medical care. All participants were diagnosed as food allergic (i.e. with a suggestive history and corresponding positive IgE). HRQL was measured using the Food Allergy Quality of Life Questionnaire--Adult Form (FAQLQ-AF). A food allergy independent measure (FAIM) was used to evaluate the adult's perception of the severity of his/her disease. RESULTS: Total FAQLQ-AF score in individuals who never visited a doctor for their FA was significantly lower than that of patients who sought medical care (2.4 vs. 3.9, p = 0.03), indicating that the former had a better quality of life than patients who did seek medical care. Regarding the different domains of FAQLQ, the score for allergen avoidance and dietary restrictions and the score for emotional impact (EI) was significantly higher in the group that sought medical care (p = 0.02 and 0.03, respectively), indicating the importance of these domains. The FAIM score was significantly higher in the group that sought medical care, indicating that they perceived their FA as more severe. CONCLUSION AND CLINICAL RELEVANCE: Patients who seek medical care for their FA have a more impaired HRQL and perceive their FA as more severe. Food avoidance and issues related to the EI of FA are key areas of intervention aimed at improving HRQL in patients with FA.

Food allergy knowledge of parents - is ignorance bliss?

BACKGROUND: Food allergic children are at least partially dependent on their parents to care for their food allergy. In addition, parents are often responsible for the education of others regarding food allergy, including the family, school, neighbors, and friends. The aim of this study was to investigate food allergy knowledge, attitudes, and beliefs of parents with food allergic children in the Netherlands. In addition, a cross-cultural comparison was made between parents from the USA and parents from the Netherlands. METHODS: The original Chicago Food Allergy Research Survey for Parents of Children with Food Allergy (CFARS-PRNT) was translated into Dutch. Parents of children with at least one doctor-diagnosed food allergy were included. Knowledge scores and attitude/beliefs scores were determined and compared with the data from 2945 parents from the USA. Predictors of overall knowledge scores were investigated. RESULTS: Dutch parents of children completed the translated CFARS-PRNT (n = 299). The mean overall knowledge score in the Netherlands was 9.9 after adjusting for guessing, compared with 12.7 in the USA (p < 0.001). Attitudes and beliefs regarding food allergy among parents from the Netherlands were generally more optimistic. The overall knowledge scores could be predicted by country of origin, educational degree, being member of a patient organization, visiting an allergist, and a history of anaphylaxis. CONCLUSIONS: Food allergy knowledge among parents of food allergic children from the Netherlands is suboptimal when compared with their counterparts from the USA, although these parents tend to be more optimistic toward food allergy than parents from the USA.

Food allergy and quality of life: what have we learned?

Health-related quality of life (HRQL) has become an emerging focus of interest in food allergy. Food allergy is a disease characterized by low mortality and symptoms which only occur during an allergic reaction. However, food-allergic patients continuously need to be alert when eating in order to prevent potentially severe allergic reactions, which may be fatal. Fear of such reactions and the need to be continuously vigilant may seriously compromise their HRQL. During the last decade, numerous studies have been published on food allergy and HRQL. The development of reliable, valid and responsive instruments for measuring HRQL in food allergic patients has facilitated this research even further. Such instruments have given insight into the specific problems a patient may face and the impact of food allergy-related interventions from the patient's perspective. This paper focuses on the most significant findings regarding this topic since its first appearance in the literature in 2000.

Health sector costs of self-reported food allergy in Europe: a patient-based cost of illness study.

INTRODUCTION: Food allergy is a recognized health problem, but little has been reported on its cost for health services. The EuroPrevall project was a European study investigating the patterns, prevalence and socio-economic cost of food allergy. AIMS: To investigate the health service cost for food-allergic Europeans and the relationship between severity and cost of illness. METHODS: Participants recruited through EuroPrevall studies in a case-control study in four countries, and cases only in five countries, completed a validated economics questionnaire. Individuals with possible food allergy were identified by clinical history, and those with food-specific immunoglobulin E were defined as having probable allergy. Data on resource use were used to estimate total health care costs of illness. Mean costs were compared in the case-control cohorts. Regression analysis was conducted on cases from all 9 countries to assess impact of country, severity and age group. RESULTS: Food-allergic individuals had higher health care costs than controls. The mean annual cost of health care was international dollars (I$)2016 for food-allergic adults and I$1089 for controls, a difference of I$927 (95% confidence interval I$324-I$1530). A similar result was found for adults in each country, and for children, and was not sensitive to baseline demographic differences. Cost was significantly related to severity of illness in cases in nine countries. CONCLUSIONS: Food allergy is associated with higher health care costs. Severity of allergic symptoms is a key explanatory factor.

Food allergy-related quality of life after double-blind, placebo-controlled food challenges in adults, adolescents, and children.

BACKGROUND: Currently, the longitudinal validity (validity over time) and responsiveness (ability to measure change over time) of the Food Allergy Quality of Life Questionnaire-Adult Form (FAQLQ-AF), the Food Allergy Quality of Life Questionnaire-Teenager Form (FAQLQ-TF), and the Food Allergy Quality of Life Questionnaire-Child Form (FAQLQ-CF) are unknown. Additionally, the self-reported impact of a double-blind, placebo-controlled food challenge (DBPCFC) on health-related quality of life (HRQL) in adults (≥18 years of age), adolescents (13-17 years of age), and children (8-12 years of age) is unknown. OBJECTIVE: The aims of this study were to assess the longitudinal validity and responsiveness of the FAQLQ-AF, FAQLQ-TF, and FAQLQ-CF and to assess the impact of a DBPCFC on HRQL. METHODS: Two hundred twenty-one participants suspected of food allergy were included from Dutch allergy centers. Participants undergoing a DBPCFC (experimental group) completed the FAQLQ and Food Allergy Independent Measure (FAIM) 1 month before (baseline) and 6 months after (follow-up) a DBPCFC. Participants not undergoing a DBPCFC (control group) completed the questionnaire package twice with a 7-month interval. RESULTS: HRQL scores improved after a DBPCFC, with greater improvements in HRQL scores after a negative outcome (food allergy ruled out) than a positive outcome (food allergy confirmed), demonstrating responsiveness of the FAQLQs. Significant correlations were shown between the change (follow-up minus baseline) in FAQLQ and FAIM scores supporting longitudinal validity of these questionnaires: FAQLQ-AF (Pearson correlation coefficient = 0.71, P < .001), FAQLQ-TF (Pearson correlation coefficient = 0.35, P = .018), and FAQLQ-CF (Pearson correlation coefficient = 0.51, P < .001). CONCLUSIONS: Our findings demonstrate the longitudinal validity and responsiveness of the FAQLQs. Greater improvements in HRQL scores were shown after a negative outcome than after a positive outcome.