Core outcome measurement set for research and clinical practice in post-COVID-19 condition (long COVID) in children and young people: an international Delphi consensus study "PC-COS Children".

The coronavirus disease 2019 (COVID-19) pandemic substantially impacted different age groups, with children and young people not exempted. Many have experienced enduring health consequences. Presently, there is no consensus on the health outcomes to assess in children and young people with post-COVID-19 condition. Furthermore, it is unclear which measurement instruments are appropriate for use in research and clinical management of children and young people with post-COVID-19. To address these unmet needs, we conducted a consensus study, aiming to develop a core outcome set (COS) and an associated core outcome measurement set (COMS) for evaluating post-COVID-19 condition in children and young people. Our methodology comprised of two phases. In phase 1 (to create a COS), we performed an extensive literature review and categorisation of outcomes, and prioritised those outcomes in a two-round online modified Delphi process followed by a consensus meeting. In phase 2 (to create the COMS), we performed another modified Delphi consensus process to evaluate measurement instruments for previously defined core outcomes from phase 1, followed by an online consensus workshop to finalise recommendations regarding the most appropriate instruments for each core outcome. In phase 1, 214 participants from 37 countries participated, with 154 (72%) contributing to both Delphi rounds. The subsequent online consensus meeting resulted in a final COS which encompassed seven critical outcomes: fatigue; post-exertion symptoms; work/occupational and study changes; as well as functional changes, symptoms, and conditions relating to cardiovascular, neuro-cognitive, gastrointestinal and physical outcomes. In phase 2, 11 international experts were involved in a modified Delphi process, selecting measurement instruments for a subsequent online consensus workshop where 30 voting participants discussed and independently scored the selected instruments. As a result of this consensus process, four instruments met a priori consensus criteria for inclusion: PedsQL multidimensional fatigue scale for "fatigue"; PedsQL gastrointestinal symptom scales for "gastrointestinal"; PedsQL cognitive functioning scale for "neurocognitive" and EQ-5D for "physical functioning". Despite proposing outcome measurement instruments for the remaining three core outcomes ("cardiovascular", "post-exertional malaise", "work/occupational and study changes"), a consensus was not achieved. Our international, consensus-based initiative presents a robust framework for evaluating post-COVID-19 condition in children and young people in research and clinical practice via a rigorously defined COS and associated COMS. It will aid in the uniform measurement and reporting of relevant health outcomes worldwide.

EAACI guidelines on the management of IgE-mediated food allergy.

This European Academy of Allergy and Clinical Immunology (EAACI) guideline provides recommendations for the management of IgE-mediated food allergy and was developed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. Following the confirmation of IgE-mediated food allergy diagnosis, allergen avoidance and dietary advice (with support of a specialised dietitian, if possible) together with the provision of a written treatment plan, education on the recognition of allergic symptoms and prescription of medication including adrenaline using an auto-injector are essential. Patients with significant anxiety and requirement for coping strategies may benefit from support from a clinical psychologist. As immunomodulatory interventions, omalizumab is suggested for treatment of IgE-mediated food allergy in children from the age of 1 and adults; and oral allergen-specific immunotherapy is recommended for children and adolescents with peanut allergy and suggested for milk and egg allergies (generally after 4 years of age for milk and egg). Sublingual and epicutaneous immunotherapy are suggested for peanut allergy but are not yet available at the point of care. Future research into disease modifying treatments for IgE-mediated food allergy are highly needed, with standardised and patient-focused protocols and outcomes.

Evaluation of clinical outcomes of efficacy in food allergen immunotherapy trials, COFAITH EAACI task force.

Food allergy is a global public health problem that until recent years lacked any aetiological treatment supported by academy, industry and regulators. Food immunotherapy (AIT) is an evolving treatment option, supported by clinical practice and industry trial data. Recent AIT meta-analyses have highlighted the difficulty in pooling safety and efficacy data from AIT trials, due to secondary heterogeneity in the study. An EAACI task force (CO-FAITH) initiated by the Paediatric Section was created to focus on AIT efficacy outcomes for milk, egg and peanut allergy rather than in trial results. A systematic search and a narrative review of AIT controlled clinical trials and large case series was conducted. A total of 63 manuscripts met inclusion criteria, corresponding to 23, 21 and 22 studies of milk, egg and peanut AIT, respectively. The most common AIT efficacy outcome was desensitization, mostly defined as tolerating a maintenance phase dose, or reaching a particular dose upon successful exit oral food challenge (OFC). However, a large degree of heterogeneity was identified regarding the dose quantity defining this outcome. Sustained unresponsiveness and patient-reported outcomes (e.g. quality of life) were explored less frequently, and to date have been most rigorously described for peanut AIT versus other allergens. Change in allergen threshold assessed by OFC remains the most common efficacy measure, but OFC methods suffer from heterogeneity and methodological disparity. This review has identified multiple heterogeneous outcomes related to measuring the efficacy of AIT. Efforts to better standardize and harmonize which outcomes, and how to measure them must be carried out to help in the clinical development of safe and efficacious food allergy treatments.

Telemedicine with special focus on allergic diseases and asthma-Status 2022: An EAACI position paper.

Efficacious, effective and efficient communication between healthcare professionals (HCP) and patients is essential to achieve a successful therapeutic alliance. Telemedicine (TM) has been used for decades but during the COVID-19 pandemic its use has become widespread. This position paper aims to describe the terminology and most important forms of TM among HCP and patients and review the existing studies on the uses of TM for asthma and allergy. Besides, the advantages and risks of TM are discussed, concluding that TM application reduces costs and time for both, HCP and patients, but cannot completely replace face-to-face visits for physical examinations and certain tests that are critical in asthma and allergy. From an ethical point of view, it is important to identify those involved in the TM process, ensure confidentiality and use communication channels that fully guarantee the security of the information. Unmet needs and directions for the future regarding implementation, data protection, privacy regulations, methodology and efficacy are described.

EAACI guidelines on the diagnosis of IgE-mediated food allergy.

This European Academy of Allergy and Clinical Immunology guideline provides recommendations for diagnosing IgE-mediated food allergy and was developed using the Grading of Recommendations, Assessment, Development and Evaluations (GRADE) approach. Food allergy diagnosis starts with an allergy-focused clinical history followed by tests to determine IgE sensitization, such as serum allergen-specific IgE (sIgE) and skin prick test (SPT), and the basophil activation test (BAT), if available. Evidence for IgE sensitization should be sought for any suspected foods. The diagnosis of allergy to some foods, such as peanut and cashew nut, is well supported by SPT and serum sIgE, whereas there are less data and the performance of these tests is poorer for other foods, such as wheat and soya. The measurement of sIgE to allergen components such as Ara h 2 from peanut, Cor a 14 from hazelnut and Ana o 3 from cashew can be useful to further support the diagnosis, especially in pollen-sensitized individuals. BAT to peanut and sesame can be used additionally. The reference standard for food allergy diagnosis is the oral food challenge (OFC). OFC should be performed in equivocal cases. For practical reasons, open challenges are suitable in most cases. Reassessment of food allergic children with allergy tests and/or OFCs periodically over time will enable reintroduction of food into the diet in the case of spontaneous acquisition of oral tolerance.

Proposal of 0.5 mg of protein/100 g of processed food as threshold for voluntary declaration of food allergen traces in processed food-A first step in an initiative to better inform patients and avoid fatal allergic reactions: A GA²LEN position paper.

BACKGROUND: Food anaphylaxis is commonly elicited by unintentional ingestion of foods containing the allergen above the tolerance threshold level of the individual. While labeling the 14 main allergens used as ingredients in food products is mandatory in the EU, there is no legal definition of declaring potential contaminants. Precautionary allergen labeling such as "may contain traces of" is often used. However, this is unsatisfactory for consumers as they get no information if the contamination is below their personal threshold. In discussions with the food industry and technologists, it was suggested to use a voluntary declaration indicating that all declared contaminants are below a threshold of 0.5 mg protein per 100 g of food. This concentration is known to be below the threshold of most patients, and it can be technically guaranteed in most food production. However, it was also important to assess that in case of accidental ingestion of contaminants below this threshold by highly allergic patients, no fatal anaphylactic reaction could occur. Therefore, we performed a systematic review to assess whether a fatal reaction to 5mg of protein or less has been reported, assuming that a maximum portion size of 1kg of a processed food exceeds any meal and thus gives a sufficient safety margin. METHODS: MEDLINE and EMBASE were searched until 24 January 2021 for provocation studies and case reports in which one of the 14 major food allergens was reported to elicit fatal or life-threatening anaphylactic reactions and assessed if these occurred below the ingestion of 5mg of protein. A Delphi process was performed to obtain an expert consensus on the results. RESULTS: In the 210 studies included, in our search, no reports of fatal anaphylactic reactions reported below 5 mg protein ingested were identified. However, in provocation studies and case reports, severe reactions below 5 mg were reported for the following allergens: eggs, fish, lupin, milk, nuts, peanuts, soy, and sesame seeds. CONCLUSION: Based on the literature studied for this review, it can be stated that cross-contamination of the 14 major food allergens below 0.5 mg/100 g is likely not to endanger most food allergic patients when a standard portion of food is consumed. We propose to use the statement "this product contains the named allergens in the list of ingredients, it may contain traces of other contaminations (to be named, e.g. nut) at concentrations less than 0.5 mg per 100 g of this product" for a voluntary declaration on processed food packages. This level of avoidance of cross-contaminations can be achieved technically for most processed foods, and the statement would be a clear and helpful message to the consumers. However, it is clearly acknowledged that a voluntary declaration is only a first step to a legally binding solution. For this, further research on threshold levels is encouraged.

A multi-disciplinary approach to the diagnosis and management of allergic diseases: An EAACI Task Force.

BACKGROUND: Guidelines for management of patients with allergic conditions are available, but the added value of nurses, allied healthcare professionals (AHPs), and general practitioners (GPs), in the management of allergic disease, has not been fully clarified. The European Academy of Allergy and Clinical Immunology (EAACI) appointed a task force to explore this issue. AIM: To investigate the added value of nurses, AHPs, and GPs in management of allergic diseases, in an integrated model of care. METHODS: A search was made of peer-reviewed literature published between 2010 and December 2020 (Cochrane Library, PubMed, and CINAHL) on the involvement of the various specific healthcare providers (HCPs) in the management of allergic diseases. RESULTS: Facilitative models of care for patients with allergies can be achieved if HCP collaborates in the diagnosis and management. Working in multi-disciplinary teams (MDT) can increase patients' understanding of the disease, adherence to treatment, self-care capabilities, and ultimately improve quality of life. The MDT competencies and procedures can be improved and enhanced in a climate of mutual respect and shared values, and with inclusion of patients in the planning of care. Patient-centered communication among HCPs and emphasis on the added value of each profession can create an effective integrated model of care for patients with allergic diseases. CONCLUSION: Nurses, AHPs, and GPs, both individually and in collaboration, can contribute to the improvement of the management of patients with allergic disease. The interaction between the HCPs and the patients themselves can ensure maximum support for people with allergies.

Dissemination of EAACI food allergy guidelines using a flexible, practical, whole school allergy awareness toolkit.

BACKGROUND: Essential training for emergency adrenaline auto-injector administration alone provides an inadequate safeguard in school environments. Recent UK deaths have reinforced the urgency for embedding whole school (WS) allergy awareness to minimise risk. We documented the development of a practical, flexible WS Food Allergy Awareness Toolkit for UK secondary schools. METHODS: We used a multidisciplinary participatory action research methodology, involving successive modification and retesting of a pragmatic toolkit in 3 case study schools. A School Allergy Action Group drives WS risk assessment, helping schools gradually implement best practice policy in line with their particular needs. Additional schools self-piloted the resulting toolkit with only remote monitoring. School surveys, based on EAACI guidelines were developed to identify priorities and assess change. RESULTS: Effectiveness of the resulting process toolkit, now available online, was independently demonstrated via pre/post-intervention questionnaires from 24/10 pupils with food allergy (FA) and 97/6 pupils without FA, respectively. Pearson correlational analysis showed strong negative relationships between Food Allergy Quality of Life Questionnaire (FAQLQ) at T0 and School Support (SS) at T0 (r = -0.8, P<0.01), and between SS and Self-Efficacy (SE) (r = 0.73, P<0.05). Mean FAQLQ scores improved between T0 (3.3) and T1 (2.5). SE improved for those with FA (mean difference = 1.0). In those without FA, SE (mean difference = 0.9) and Attitudes and Knowledge (mean difference = 0.7) also improved. CONCLUSIONS: Full stakeholder involvement in toolkit development encourages usage and, therefore, improves WS community awareness; reduces risk of reactions; fosters a more accepting societal attitude and empowers pupils with/without allergies to self-manage effectively.

Identifying and managing patients at risk of severe allergic reactions to food: Report from two iFAAM workshops.

Food allergy affects a small but important number of children and adults. Much of the morbidity associated with food allergy is driven by the fear of a severe reaction and fatalities continue to occur. Foods are the commonest cause of anaphylaxis. One of the aims of the European Union-funded Integrated Approaches to Food Allergen and Allergy Risk Management (iFAAM) project was to improve the identification and management of children and adults at risk of experiencing a severe reaction. A number of interconnected studies within the project have focused on quantifying the severity of allergic reactions; the impact of food matrix, immunological factors on severity of reactions; the impact of co-factors such as medications on the severity of reactions; utilizing single-dose challenges to understand threshold and severity of reactions; and community studies to understand the experience of patients suffering real-life allergic reactions to food. Associated studies have examined population thresholds and co-factors such as exercise and stress. This paper summarizes two workshops focused on the severity of allergic reactions to food. It outlines the related studies being undertaken in the project indicating how they are likely to impact on our ability to identify individuals at risk of severe reactions and improve their management.

Validation of a health-related quality of life instrument for primary ciliary dyskinesia (QOL-PCD).

BACKGROUND: Quality of life (QOL)-primary ciliary dyskinesia (PCD) is the first disease-specific, health-related QOL instrument for PCD. Psychometric validation of QOL-PCD assesses the performance of this measure in adults, including its reliability, validity and responsiveness to change. METHODS: Seventy-two adults (mean (range) age: 33 years (18-79 years); mean (range) FEV1% predicted: 68 (26-115)) with PCD completed the 49-item QOL-PCD and generic QOL measures: Short-Form 36 Health Survey, Sino-Nasal Outcome Test 20 (SNOT-20) and St George Respiratory Questionnaire (SGRQ)-C. Thirty-five participants repeated QOL-PCD 10-14 days later to measure stability or reproducibility of the measure. RESULTS: Multitrait analysis was used to evaluate how the items loaded on 10 hypothesised scales: physical, emotional, role and social functioning, treatment burden, vitality, health perceptions, upper respiratory symptoms, lower respiratory symptoms and ears and hearing symptoms. This analysis of item-to-total correlations led to 9 items being dropped; the validated measure now comprises 40 items. Each scale had excellent internal consistency (Cronbach's α: 0.74 to 0.94). Two-week test-retest demonstrated stability for all scales (intraclass coefficients 0.73 to 0.96). Significant correlations were obtained between QOL-PCD scores and age and FEV1. Strong relationships were also found between QOL-PCD scales and similar constructs on generic questionnaires, for example, lower respiratory symptoms and SGRQ-C (r=0.72, p<0.001), while weak correlations were found between measures of different constructs. CONCLUSIONS: QOL-PCD has demonstrated good internal consistency, test-retest reliability, convergent and divergent validity. QOL-PCD offers a promising tool for evaluating new therapies and for measuring symptoms, functioning and QOL during routine care.

The patient's experience of primary ciliary dyskinesia: a systematic review.

BACKGROUND: Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterised by progressive sinopulmonary disease, with symptoms starting soon after birth. The aim of this study is to critically review, analyse, and synthesise the literature in order to understand the experiences of patients with primary ciliary dyskinesia (PCD) and the impact on health-related quality of life. METHOD: MEDLINE, EBSCO, Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycINFO and EMBASE were searched according to the inclusion criteria. A qualitative analysis of 14 studies was conducted. RESULTS: Fourteen studies were included in the review, five with qualitative methodologies. Studies originated from the UK, USA, Italy, Denmark and Belgium, one study included a survey distributed internationally. Significant relationships were found between age and worsening of respiratory symptoms, physical, and mental domains of health-related quality of life, with a greater decline compared with reference populations. Variations between the UK and Italy were found for health-related quality of life and its correlation with time since diagnosis. PCD was found to have a physical impact in all age groups: patients found it difficult to keep up with others, and found energy levels were easily depleted compared to family or peers. In terms of social impact, symptoms lead to embarrassment and a sense of isolation, with patients concealing symptoms and/or their diagnosis. In turn, isolation was also linked with the lack of public and medical knowledge. In relation to emotional impact, anxiety was reported in a number of qualitative studies; patients were anxious about getting sick or when thinking about their future health. The burden of treatment and factors influencing adherence were also discussed in depth. CONCLUSION: Health-related quality of life decreases with age in patients with PCD. For all age groups, PCD was found to greatly impact physical, emotional, social functioning, and treatment burden. More research is needed on the psychosocial impact of the illness, disease burden and its effect on quality of life.

Skin barrier impairment at birth predicts food allergy at 2 years of age.

BACKGROUND: Transcutaneous exposure to food allergens can lead to food sensitization (FS)/food allergy (FA). We measured skin barrier function in early infancy and related it to the later development of FS/FA at age 2 years. OBJECTIVE: We sought to examine the relationship between early life skin barrier function and FA in infancy. METHODS: Infants in the Babies After Scope: Evaluating the Longitudinal Impact Using Neurological and Nutritional Endpoints (BASELINE) birth cohort had transepidermal water loss (TEWL) measured in the early newborn period and at 2 and 6 months of age. At age 2 years, infants had FS/FA screening with skin prick tests and oral food challenges. RESULTS: One thousand nine hundred three infants were enrolled. One thousand three hundred fifty-five were retained to age 2 years, and 1260 underwent FS screening. FS was present in 6.27% (79/1260; 95% CI, 4.93% to 7.61%), and FA prevalence was 4.45% (56/1258; 95% CI, 3.38% to 5.74%). Egg was the most prevalent allergen (2.94%), followed by peanut (1.75%) and cow's milk (0.74%). Day 2 upper-quartile TEWL (>9 g water/m(2)/h) was a significant predictor of FA at age 2 years (odds ratio [OR], 4.1; 95% CI, 1.5-4.8). Seventy-five percent of children with FA at 2 years of age had day 2 TEWL in the upper quartile. Even in those without atopic dermatitis (AD), infants with upper-quartile day 2 TEWL were 3.5 times more likely to have FA at 2 years than infants in the lowest quartile (95% CI, 1.3-11.1; P = .04). CONCLUSION: Neonatal skin barrier dysfunction predicts FA at 2 years of age, supporting the concept of transcutaneous allergen sensitization, even in infants who do not have AD. TEWL could be used for stratifying infants in the first few days of life before development of AD or FA for targeted intervention studies to potentially alter the atopic march.

Diagnosing primary ciliary dyskinesia: an international patient perspective.

Primary ciliary dyskinesia (PCD) is a rare genetic disorder characterised by progressive sino-pulmonary disease, with symptoms starting soon after birth. A European Respiratory Society (ERS) Task Force aims to address disparities in diagnostics across Europe by providing evidence-based clinical practice guidelines. We aimed to identify challenges faced by patients when referred for PCD diagnostic testing.A patient survey was developed by patient representatives and healthcare specialists to capture experience. Online versions of the survey were translated into nine languages and completed in 25 countries. Of the respondents (n=365), 74% were PCD-positive, 5% PCD-negative and 21% PCD-uncertain/inconclusive. We then interviewed 20 parents/patients. Transcripts were analysed thematically.35% of respondents visited their doctor more than 40 times with PCD-related symptoms prior to diagnostic referral. Furthermore, the most prominent theme among interviewees was a lack of PCD awareness among medical practitioners and failure to take past history into account, leading to delayed diagnosis. Patients also highlighted the need for improved reporting of results and a solution to the "inconclusive" diagnostic status.These findings will be used to advise the ERS Task Force guidelines for diagnosing PCD, and should help stakeholders responsible for improving existing services and expanding provision for diagnosis of this rare disease.

Skin barrier dysfunction measured by transepidermal water loss at 2 days and 2 months predates and predicts atopic dermatitis at 1 year.

BACKGROUND: Loss-of-function mutations in the skin barrier protein filaggrin (FLG) are a major risk for atopic dermatitis (AD). The pathogenic sequence of disturbances in skin barrier function before or during the early development of AD is not fully understood. A more detailed understanding of these events is needed to develop a clearer picture of disease pathogenesis. A robust, noninvasive test to identify babies at high risk of AD would be important in planning early intervention and/or prevention studies. OBJECTIVES: To ascertain whether a noninvasive measurement of skin barrier function at day 2 after birth and at 2 months predicts the development of AD at 1 year. Furthermore, to determine whether increases in transepidermal water loss (TEWL) predate the development of clinical AD. METHODS: A total of 1903 infants were enrolled in the Cork Babies After Scope: Evaluating the Longitudinal Impact Using Neurological and Nutritional Endpoints Birth Cohort study from July 2009 to October 2011. Measurements of TEWL were made at birth (day 2) and at 2 and 6 months. The presence of AD was ascertained at 6 and 12 months, and disease severity was assessed by using the SCORing Atopic Dermatitis clinical tool at 6 months and by using both the SCORing Atopic Dermatitis clinical tool and Nottingham Severity Score at 12 months. A total of 1300 infants were genotyped for FLG mutations. RESULTS: At 6 months, 18.7% of the children had AD, and at 12 months, 15.53%. In a logistic regression model, day 2 upper quartile TEWL measurement was significantly predictive of AD at 12 months (area under the receiver operating characteristic curve, 0.81; P < .05). Lowest quartile day 2 TEWL was protective against AD at 12 months. An upper quartile 2 month TEWL was also strongly predictive of AD at 12 months (area under the receiver operating characteristic curve, 0.84; P < .05). At both ages, this effect was independent of parental atopy, FLG status, or report of an itchy flexural rash at 2 months. Associations were increased when parental atopy status or child FLG mutation status was added into the linear regression model. CONCLUSIONS: Impairment of skin barrier function at birth and at 2 months precedes clinical AD. In addition to providing important mechanistic insights into disease pathogenesis, these findings have implications for the optimal timing of interventions for the prevention of AD.

A quality-of-life measure for adults with primary ciliary dyskinesia: QOL-PCD.

Primary ciliary dyskinesia (PCD) is characterised by chronic suppurative lung disease, rhino-sinusitis, hearing impairment and sub-fertility. We have developed the first multidimensional measure to assess health-related quality of life (HRQoL) in adults with PCD (QOL-PCD).Following a literature review and expert panel meeting, open-ended interviews with patients investigated the impact of PCD on HRQoL in the UK and North America (n=21). Transcripts were content analysed to derive saturation matrices. Items were rated for relevance by patients (n=49). Saturation matrices, relevance scores, literature review, evaluation of existing measures, and expert opinion contributed to development of a preliminary questionnaire. The questionnaire was refined following cognitive interviews (n=18).Open-ended interviews identified a spectrum of issues unique to adults with PCD. Saturation matrices confirmed comprehensive coverage of content. QOL-PCD includes 48 items covering the following seven domains: Physical Functioning, Emotional Functioning, Treatment Burden, Respiratory and Sinus Symptoms, Ears and Hearing, Social Functioning, and Vitality and Health Perceptions. Cognitive testing confirmed that content was comprehensive and the items were well-understood by respondents.Content validity and cognitive testing supported the items and structure. QOL-PCD has been translated into other languages and is awaiting psychometric testing.

Newborn transepidermal water loss values: a reference dataset.

Transepidermal water loss (TEWL) is a simple noninvasive measurement of inside-out skin barrier function. The goal of this research was to establish normal values for TEWL in early life using data gathered from the Cork BASELINE Birth Cohort Study. TEWL was recorded in a standardized fashion using a well-validated open-chamber system. A mean of three readings was recorded from 1,036 neonates (37-42 weeks gestational age) and 18 late preterm infants (34-37 weeks gestational age) within 96 hours of birth in an environmentally controlled room. Full-term neonatal TEWL measurements have a normal distribution (mean 7.06 ± 3.41 g of water/m(2) per hour) and mean preterm neonatal TEWL measurements were 7.76 ± 2.85 g of water/m(2) per hour. This is the largest evaluation to date of TEWL in a normal-term neonatal population. It therefore constitutes a reference dataset for this measurement using an open-chamber system.

WAO consensus on DEfinition of Food Allergy SEverity (DEFASE).

Background: While several scoring systems for the severity of anaphylactic reactions have been developed, there is a lack of consensus on definition and categorisation of severity of food allergy disease as a whole. Aim: To develop an international consensus on the severity of food allergy (DEfinition of Food Allergy Severity, DEFASE) scoring system, to be used globally. Methods Phase 1: We conducted a mixed-method systematic review (SR) of 11 databases for published and unpublished literature on severity of food allergy management and set up a panel of international experts. Phase 2: Based on our findings in Phase 1, we drafted statements for a two-round modified electronic Delphi (e-Delphi) survey. A purposefully selected multidisciplinary international expert panel on food allergy (n = 60) was identified and sent a structured questionnaire, including a set of statements on different domains of food allergy severity related to symptoms, health-related quality of life, and economic impact. Participants were asked to score their agreement on each statement on a 5-point Likert scale ranging from "strongly agree" to "strongly disagree". Median scores and percentage agreements were calculated. Consensus was defined a priori as being achieved if 70% or more of panel members rated a statement as "strongly agree" to "agree" after the second round. Based on feedback, 2 additional online voting rounds were conducted. Results: We received responses from 92% of Delphi panel members in round 1 and 85% in round 2. Consensus was achieved on the overall score and in all of the 5 specific key domains as essential components of the DEFASE score. Conclusions: The DEFASE score is the first comprehensive grading of food allergy severity that considers not only the severity of a single reaction, but the whole disease spectrum. An international consensus has been achieved regarding a scoring system for food allergy disease. It offers an evaluation grid, which may help to rate the severity of food allergy. Phase 3 will involve validating the scoring system in research settings, and implementing it in clinical practice.