Anaphylaxis risk factors for hospitalization and intensive care: A comparison between adults and children in an upstate New York emergency department

Trends and Hospital Outcomes in HOSPITAL Admissions for Anaphylaxis in Children with and without Asthma in Spain (2016-2021)

(1) Background: To assess and compare the temporal trends in the incidence, characteristics and hospital outcomes among children with and without asthma who were hospitalized with anaphylaxis in Spain from 2016 to 2021, and identify the variables associated with severe anaphylaxis among children with asthma. (2) Methods: An observational, retrospective study was conducted using a population-based database. The study population included pediatric patients with anaphylaxis. This population was stratified based on whether they had asthma. (3) Results: The number of hospital admissions was stable from 2016 to 2019, dropping in 2020 and raising to the highest number in 2021. A total of 60.63% of hospitalizations occurred in boys and the most common anaphylactic reactions were due to food consumption (67.28%), increasing over time. The in-hospital mortality (IHM) remained stable and under 1% in all the years studied. The incidence of anaphylaxis was 2.14 times higher in children with asthma than in those without asthma (IRR 2.14; 95% CI 1.87-2.44). Furthermore, it was 1.79 times higher in boys with asthma than in those without asthma (IRR 1.79; 95% CI 1.06-2.45) and 2.68 times higher in girls with asthma than in those without asthma (IRR 2.68; 95% CI 2.23-3.12). Asthma was not associated with severe anaphylaxis (OR 1.31; 95% CI 0.88-1.96). (4) Conclusions: The number of hospitalizations for anaphylaxis in children remained stable from 2016 to 2019, dropping in 2020 and recovering in 2021. IHM was low and remained stable during the study period. The incidence of hospitalizations for anaphylaxis was higher in asthmatic children than in non-asthmatics, but there were no differences in the occurrence of severe anaphylaxis among them.

Investigation of the underuse of adrenaline (epinephrine) and prognosis among patients with anaphylaxis at emergency department admission

Background

Anaphylaxis is a potentially fatal condition; in severe cases of anaphylaxis, the cardiovascular system is often heavily involved. Adrenaline (epinephrine) is a cornerstone of the initial treatment of anaphylaxis. The use of epinephrine remains below expectations in clinical practice. Whether the underuse of epinephrine affects the prognosis of patients with anaphylaxis is still unclear.

Materials and methods

This retrospective study included patients with anaphylaxis between 2011 and 2020 who were admitted to an emergency department (ED) in Taiwan. All patients were divided into two groups based on the use of epinephrine (or not), and we compared the demographic characteristics, allergens, clinical manifestations, management, and patient outcomes.

Results

We reviewed the records of 314 subjects (216 males, 98 females; mean age: 52.78 ± 16.02 years) who visited our ED due to anaphylaxis; 107 (34.1%) and 207 (65.9%) patients were categorized into the epinephrine use group and the non-epinephrine use group, respectively. Arrival via ambulance (p = 0.019), hypotension (p = 0.002), airway compromise (p < 0.001) and altered consciousness (p < 0.001) were the deciding factors for epinephrine use among anaphylactic patients in the ED. The epinephrine use group had higher rates of other inotropic agent usage and fluid challenge. More than 90% of patients received bed rest, steroids, antihistamines, and monitoring. The epinephrine use group had a longer ED length of stay (387.64 ± 374.71 vs. 313.06 ± 238.99 min, p = 0.03) and a greater need of hospitalization. Among all severe symptoms, hypotension was the most tolerated decision factor for not using epinephrine. In this retrospective analysis, some patients with serious anaphylaxis did not experience adverse outcomes or death even without the use of epinephrine at ED admission. Emergent care focuses first on the airway, breathing, and circulation (ABC) and may compensate for the underusage of epinephrine. This could be the reason why epinephrine was underused among patients with anaphylaxis in the ED.

Conclusion

In summary, early ABC management continues to play an important role in treating patients with severe anaphylaxis, even when epinephrine is not immediately available in clinical scenarios.

Efficacy and safety of food allergy oral immunotherapy in adults

BACKGROUND

Oral immunotherapy (OIT) is an emerging method for treating food allergy in children. However, data regarding adults undergoing this process are lacking.

METHODS

We retrospectively analyzed the medical records of patients with food allergy aged ≥17 years who completed OIT treatment between April 2010 and December 2020 at Shamir Medical Center. Data were compared with that of children aged 4 to <11 years and adolescents aged ≥11 to 17 treated during the same time period.

RESULTS

A total of 96 adults at a median age of 22.3 years who underwent OIT for milk (n = 53), peanut (n = 18), sesame (n = 7), egg (n = 5), and tree nuts (n = 13) were analyzed and compared with 1299 children and 309 adolescents. Adults experienced more adverse reactions requiring injectable epinephrine, both during in-clinic up-dosing (49% vs. 15.9% and 26.5% for children and adolescents, respectively, p < 0.0001) and during home treatment (22.9% vs. 12.4%, p = 0.007 for children, and 17.5%, p = 0.23 for adolescents). Most adults (61.5%) were fully desensitized, but the rates of full desensitization were significantly lower than children (73.4%, p = 0.013). Significantly more adults (28.3%) undergoing milk OIT failed treatment than children (14.3%, p = 0.015) and adolescents (14.1%, p = 0.022), while failure rates in adults undergoing OIT for other foods were low (9.3%) and comparable with children and adolescents.

CONCLUSIONS

OIT is successful in desensitizing most adults with IgE-mediated food allergy. Adults undergoing milk OIT are at increased risk for severe reactions and for OIT failure while failure rates in adults undergoing OIT for other foods are low.

Allergic multimorbidity is associated with self-reported anaphylaxis in adults-A cross-sectional questionnaire study

Background

Anaphylaxis has increased over the last two decades in Europe, reaching an estimated prevalence of 0.3% and an incidence of 1.5-7.9 per 100,000 person-years. Allergic multimorbidity is associated with asthma severity, yet its role in anaphylaxis is not fully understood. Our aim was to study association between allergic multimorbidity and anaphylaxis in adults.

Methods

We used population-based data from the Finnish Allergy Barometer Study (n = 2070, age range: 5-75). Food allergy (FA), atopic dermatitis (AD), allergic rhinitis (AR) and allergic conjunctivitis (AC), were defined from a self-completed questionnaire. A logistic regression adjusted on potential confounders (sex, age, smoking status) was applied to estimate the anaphylaxis risk associated with allergic multimorbidity.

Results

1319 adults with at least one allergic disease (FA, AD, AR, AC) with/without asthma (AS) were included. Of these, 164 had self-reported anaphylaxis [mean (SD, min-max) 54 (14, 22-75) years, 17% men]. AS, FA, AR, AC, or AD were reported by 86.0%, 62.2%, 82.3%, 43.3%, and 53.7% of subjects with anaphylaxis and respectively by 67.8%, 29.5%, 86.2%, 29.4%, and 34.4% of subjects without anaphylaxis. Compared with subjects exhibiting only one allergic disease, the risk of anaphylaxis increased with the number of allergic diseases; adjusted odds ratios (OR) [CI95%] for two, three, four and five coinciding allergic diseases were 1.80 [0.79-4.12], 3.35 [1.47-7.66], 7.50 [3.25-17.32], and 13.5 [5.12-33.09], respectively. The highest risk of anaphylaxis (6.47 [4.33-9.92]) was associated with FA + AS or their various variations with AR/AC/AD embodied, when compared with AR, AC, and AS separately or their combinations.

Conclusions

Anaphylaxis was positively associated with the number of allergic diseases a subject exhibited and with subgroups including FA and/or AS. The results can be applied when estimating the risk of anaphylaxis for individual patients.

Anaphylaxis among elderly emergency department patients in a large health system in New York

BACKGROUND

Anaphylaxis in the elderly is poorly understood.

OBJECTIVE

To elucidate demographic, clinical, and management characteristics of older adults presenting to emergency departments (EDs) with National Institute of Allergy and Infectious Diseases (NIAID) criteria-confirmed anaphylaxis vs milder, non-anaphylactic acute allergic reactions (AARs).

METHODS

A retrospective analysis of ED patients more than or equal to 65 years was conducted, using anaphylaxis International Classification of Diseases, Ninth Revision (ICD-9) codes or ICD-9-based algorithms incorporating the NIAID diagnostic criteria. Descriptive statistics were generated, and the abovementioned characteristics were compared between cohorts.

RESULTS

Of 164 eligible visits, 71 (43.3%), 90 (54.9%), and 3 (1.8%) cases were identified by ICD-9 codes, the algorithms, or both, respectively. Only half fulfilled NIAID diagnostic criteria. Compared with the non-anaphylactic AAR group, criteria-confirmed anaphylaxis group had lower drug allergy rates (43.9% vs 61.0%, P = .03) but higher food allergy rates (26.8% vs 12.2%, P = .02). For the criteria-confirmed anaphylaxis group, presenting signs and symptoms in descending frequency were mucocutaneous, respiratory, cardiovascular, and gastrointestinal. Criteria-confirmed anaphylaxis group had higher rates of prior anaphylaxis (13.4% vs 2.4%, P = .009), pre-ED (12.2% vs 0.0%, P = .001) or ED (72.0% vs 4.9%, P < .001) epinephrine administration, and allergy referral (17.1% vs 2.4%, P = .002). Tryptase levels were rarely ordered, occurring once in the criteria-confirmed anaphylaxis group and never in the non-anaphylactic AAR group. Despite low mortality (n = 1), 64.6% of the criteria-confirmed anaphylaxis cohort required hospitalization, with 23.2% admitted to intensive care unit.

CONCLUSION

Diagnosis of elderly ED patients with anaphylaxis remains suboptimal. Identifying NIAID criteria-confirmed cases remain challenging, using the existing methods. Management of these patients poorly adheres to current guidelines.

Drug-Related Hypersensitivity Reactions Leading to Emergency Department: Original Data and Systematic Review

The aim of the present study is to describe pharmacological characteristics of drug-related allergies and anaphylaxis leading to the emergency department (ED). An 8-year post hoc analysis on the MEREAFaPS Study database was performed (2012−2019). Subjects who experienced drug-related hypersensitivity leading to an ED visit were selected. Logistic regression analyses were used to estimate the reporting odds ratios (RORs) of drug-related allergies and anaphylaxis adjusting for sex, age classes, and ethnicity. In addition, a systematic review of observational studies evaluating drug-related hypersensitivity reactions leading to ED visits in outpatients was performed. Out of 94,073 ED visits, 14.4% cases were drug-related allergies and 0.6% were anaphylaxis. Females accounted for 56%. Multivariate logistic regression showed a higher risk of drug-related allergy among males and all age classes < 65 years, while a higher risk of anaphylaxis was observed for females (ROR 1.20 [1.01−1.42]) and adults (ROR 2.63 [2.21−3.14]). The systematic review included 37 studies. ED visits related to allergy and anaphylaxis ranged from 0.004% to 88%, and drug-related allergies and anaphylaxis ranged from 0.007% to 88%. Both in our analysis and in primary studies, antibacterials, analgesics, and radiocontrast agents were identified as the most common triggers of hypersensitivity.

Use of multiple epinephrine doses in anaphylaxis: A systematic review and meta-analysis

BACKGROUND

Regulatory bodies recommend that all patients at risk of anaphylaxis be prescribed 2 epinephrine autoinjectors, which they should carry at all times. This is in contrast to some guidelines. The proportion of anaphylaxis reactions that are treated with multiple doses of epinephrine has not been systematically evaluated.

OBJECTIVE

Our aim was to undertake a systematic review and meta-analysis of published studies reporting epinephrine treatment for anaphylaxis in which data relating to the number of doses administered were available.

METHODS

We searched the Medline, Embase, and Cochrane databases for relevant studies reporting at least 10 anaphylaxis events (due to food or venom) from 1946 until January 2020. Data were extracted in duplicate for the meta-analysis, and the risk of bias was assessed. The study was registered under the PROSPERO identifier CRD42017069109.

RESULTS

A total of 86 studies (36,557 anaphylaxis events) met the inclusion criteria (20 of the studies [23%] were prospective studies; 64 [74%] reported reactions in the community, and 22 [26%] included food challenge data). Risk of bias was assessed as low in 50 studies. Overall, 7.7% of anaphylaxis events from any cause (95% CI = 6.4-9.1) were treated with multiple doses of epinephrine. When only epinephrine-treated reactions for which subsequent doses were administered by a health care professional were considered, 11.1% of food-induced reactions (95% CI = 9.4-13.2) and 17.1% of venom-induced reactions (95% CI = 11.3-25.0) were treated with more than 1 epinephrine dose. Heterogeneity was moderate to high in the meta-analyses, but at sensitivity analysis this estimate was not affected by study design or anaphylaxis definition.

CONCLUSION

Around 1 in 10 anaphylaxis reactions are treated with more than 1 dose of epinephrine.

Is the clinical manifestation of anaphylaxis in children influenced by the trigger of reaction?

INTRODUCTION

The number of anaphylaxis diagnoses in children is rising, being still based on the clinical picture.

AIM

To determine whether triggers of anaphylaxis influence its clinical characteristics in children and adolescents.

MATERIAL AND METHODS

The study group included 114 children (5 months-17 years, mean age: 8.0 ±4.8 years), (66%: boys) with the episode of anaphylaxis up to 1 year back. Medical data were entered to the NORA Registry by means of a validated structured on-line questionnaire.

RESULTS

Three most frequent triggers of anaphylaxis were: insect venom (47.4%), food (35.1%), drugs (5.3%), with a predominance of food (egg white, cow's milk, nuts and peanuts) in the 0-6 years age group, while insect venom (bee predominance) in the 7-17 years age group (p = 0.016). Clinical manifestations differed between food vs. venom allergic reactions and presented as gastro-intestinal (GI) (61.4%) (p = 0.004), respiratory (RS) (93.9%) (p = 0.036), and cardiovascular (CVS) (74.6%) (p = 0.022) symptoms. Among objective symptoms, vomiting was the most common symptom in the 0-2 years age group (47.1%) (p = 0.006), while hypotension in those aged 7-12 years (40%) (p = 0.010). Severity of symptoms evaluated as Mueller's grade (IV - 74.5%) and as Ring and Messmer's grade (III - 65.8%), depended on the trigger (p = 0.028, p = 0.029, respectively). Life-threatening symptoms occurred in 26 children (fall of the blood pressure - 22%, loss of consciousness - 4.4%).

CONCLUSIONS

The clinical manifestation of anaphylaxis in children is both trigger and age dependent, irrespective of the gender. A typical patient with food anaphylaxis was younger, presenting predominantly GI symptoms, while a typical patient with venom anaphylaxis was older, with mostly cardiovascular symptoms.

Health-care resource utilization associated with peanut allergy management under allergen avoidance among commercially insured individuals

Background: Until recently, the standard approach to care for individuals with peanut allergy (PA) was limited to allergen avoidance and treatment of reactions with emergency medicines. Objectives: To assess health-care resource utilization (HRU) and costs associated with PA management under allergen avoidance and to identify risk factors associated with peanut reactions that resulted in inpatient (IP) and/or emergency department (ED) visits. Methods: Privately insured individuals with PA diagnosis codes were identified from a large U.S. administrative claims data base (January 1, 1999, to March 31, 2017). PA-related HRU, indicated by a PA diagnosis and/or diagnostic procedure codes and by epinephrine autoinjectors (EAI) prescription fills in medical and pharmacy claims, respectively, and all-cause costs were described per patient-year (PPY). Risk factors associated with peanut reactions in an IP and/or ED setting were identified by using a multivariable logistic regression model. Results: A total of 86,483 patient-years from 14,136 individuals with PA were included. At the patient-year level, 28.1% were ages 0-3 years, 43.6% were ages 4-11 years, 13.7% were ages 12-17 years, and 14.5% were ages ≥ 18 years; 35.6% had PA-related outpatient visits; 50.6% had EAI fills; and 2.4% had PA-related IP and/or ED visits PPY. Younger individuals had more PA-related outpatient visits and EAI fills, with peak intensive use at ages 4-11 years. The proportion of individuals with PA-related IP and/or ED visits was highest among those aged ≥ 18 years. Mean all-cause costs were $3084 PPY; individuals with PA-related IP and/or ED visits incurred $8902 PPY ($17,451 for those with one or more IP visits). Risk factors associated with peanut reactions that resulted in IP and/or ED visits included young adults (odds ratio [OR] 3.19 [95% confidence interval {CI}, 2.66-3.83]), previous peanut reaction(s) (OR 1.66 [95% CI, 1.23-2.24]), asthma (OR 1.33 [95% CI, 1.18-1.51]), and male sex (OR 1.14 [95% CI, 1.01-1.28]). Conclusion: Individuals with PA and under allergen avoidance had significant HRU that varied across all age groups, with more PA-related outpatient visits during preschool and/or school age and PA-related urgent care among adults. Individuals with previous peanut reaction(s), asthma, and males had a higher risk of peanut reactions that resulted in IP and/or ED visits.

Digital technology for anaphylaxis management impact on patient behaviour: A randomized clinical trial

BACKGROUND

Epinephrine is the first-line treatment for anaphylaxis. Patients at risk should always carry an epinephrine autoinjector (EAI). Several EAI gaps have been identified. We sought to evaluate satisfaction using a medical device (digital technology comprising an EAI smart case connected to a mobile APP) with functions that overcome most of the EAI limitations and to determine whether patient behaviour and anaphylaxis management improve with its use.

METHODS

This was a randomized, open-label, crossover clinical trial in a tertiary hospital involving patients with history of anaphylaxis carrying an EAI. The study was conducted in two three-month periods, one with and one without the medical device. The primary endpoint was satisfaction with the medical device. Usability, adherence, anxiety and anaphylaxis episodes were evaluated as secondary endpoints.

RESULTS

A total of 100 patients were included (mean age 38.1 years, 74% female), and 95 completed the trial. The satisfaction visual analogue scale (VAS) after using the medical device was higher than before its use (89.1 [95% CI, 60.2-99.1] vs 56.3 [95% CI, 48.1-81.4]; P < .0001). The adherence VAS improved from 59.7 (95% CI, 54.0-65.3) to 88.6 (95% CI, 84.2-92.9) (P < .0001). Overall, 90% patients found the medical device easy to use. Patients' anxiety decreased from 52.2% to 29.3% (P < .001). Seven episodes of anaphylaxis occurred during the study, all in patients without the medical device (P = .025). Eighty-eight per cent of patients felt more involved in the management of anaphylaxis when using the medical device.

CONCLUSION

This is the first clinical trial evaluating digital technology for EAIs, showing a change of behaviour in patients at risk of anaphylaxis, increasing satisfaction, improving adherence, and reducing anxiety, with good usability.

Community Use of Epinephrine for the Treatment of Anaphylaxis: A Review and Meta-Analysis

BACKGROUND

Community use of epinephrine for the treatment of anaphylaxis is low. Knowledge of rates of epinephrine use in the pre-hospital setting along with identification of barriers to its use will contribute to the development of policies and guidelines.

OBJECTIVES

A search was conducted on PubMed and Embase in April 2020. Our systematic review focused on 4 domains: (1) epinephrine use in the pre-hospital setting; (2) barriers to epinephrine use in the pre-hospital setting; (3) cost evaluation and cost-effectiveness of epinephrine use; and (4) programs and strategies to improve epinephrine use during anaphylaxis.

METHODS

Two meta-analyses with logit transformation were conducted to: (1) calculate the pooled estimate of the rate of epinephrine use in the pre-hospital setting among cases of anaphylaxis and (2) calculate the pooled estimate of the rate of biphasic reactions among all cases of anaphylaxis.

RESULTS

Epinephrine use in the pre-hospital setting was significantly higher for children compared with adults (20.98% [95% confidence interval (CI): 16.38%, 26.46%] vs 7.17% [95% CI: 2.71%, 17.63%], respectively, P = .0027). The pooled estimate of biphasic reactions among all anaphylaxis cases was 3.92% (95% CI: 2.88%, 5.32%). Our main findings indicate that pre-hospital use of epinephrine in anaphylaxis remains suboptimal. Major barriers to the use of epinephrine were identified as low prescription rates of epinephrine autoinjectors and lack of stock epinephrine in schools, which was determined to be cost-effective. Finally, in reviewing programs and strategies, numerous studies have engineered effective methods to promote adequate and timely use of epinephrine.

CONCLUSION

The main findings of our study demonstrated that across the globe, prompt epinephrine use in cases of anaphylaxis remains suboptimal. For practical recommendations, we would suggest considering stock epinephrine in schools and food courts to increase the use of epinephrine in the community. We recommend use of pamphlets in public areas (ie, malls, food courts, etc.) to assist in recognizing anaphylaxis and after that with prompt epinephrine administration, to avoid the rare risk of fatality in anaphylaxis cases.

Self-injectable epinephrine: doctors' attitude and patients' adherence in real-life

PURPOSE OF REVIEW

Epinephrine is the only life-saving treatment of anaphylaxis. Prescription and administration rates of self-injectable epinephrine are generally low. It is unclear whether this is because of availability, low prescription rates, fear of using epinephrine, or a combination of these issues.

RECENT FINDINGS

This review focuses on what self-injectable epinephrine devices (SIED), such as auto-injectors and prefilled syringes, are preferred by patients and healthcare professionals (HCP). Our findings suggest that a device's ease to use, proper and frequent training on its operability, and availability have an impact on preferences and adherence to treatment with SIEDs. After prescribing a patient with a SIED, clinicians should emphasize its use in anaphylaxis, educate patients/caregivers to identify anaphylaxis and on how to use the SIED, and encourage constant practicing with training devices.

SUMMARY

Epinephrine is the sole recommended anaphylaxis treatment and SIEDs are of critical usefulness in the community setting. Further studying of these devices is needed to optimize education for HCPs and patients and their accessibility to SIEDs.

Characteristics and Treatment of Anaphylaxis in Children Visiting a Pediatric Emergency Department in Korea

Anaphylaxis is a serious life-threatening allergic disease in children. This study is aimed at determining the characteristics of pediatric patients who experienced anaphylaxis along with treatments administered in order to determine the usefulness of tryptase level assessment as a marker of anaphylaxis in Korean children. A total of 107 patients who were diagnosed with anaphylaxis in a single pediatric emergency center over a 3-year period were included in the study. Patient clinical characteristics, symptoms, signs, allergy history, trigger factors, treatments, and laboratory findings, including serum tryptase levels, were included in the analysis. Food allergies (39.3%) were the most commonly reported patient allergic history, and 58 patients (54.2%) were triggered by food. Among this group, nuts and milk exposure were the most common, affecting 15 patients (25.9%). History of anaphylaxis and asthma were more common in severe anaphylaxis compared to mild or moderate anaphylaxis cases. Epinephrine intramuscular injection was administrated to 76 patients (71.0%), and a self-injectable epinephrine was prescribed to 18 patients (16.8%). The median tryptase level was 4.80 ng/mL (range: 2.70-10.40) which was lower than the 11.4 ng/mL value commonly documented for standard evaluation in adults with anaphylaxis. The most common cause of pediatric anaphylaxis was food including nuts and milk. The rate of epinephrine injection was relatively high in our pediatric emergency department. The median tryptase level associated with anaphylaxis reactions in children was lower than 11.4 ng/mL. Further studies are needed to help improve diagnostic times and treatment accuracy in pediatric patients who develop anaphylaxis.

Global Trends in Anaphylaxis Epidemiology and Clinical Implications

The true global scale of anaphylaxis remains elusive, because many episodes occur in the community without presentation to health care facilities, and most regions have not yet developed reliable systems with which to monitor severe allergic events. The most robust data sets currently available are based largely on hospital admissions, which are limited by inherent issues of misdiagnosis, misclassification, and generalizability. Despite this, there is convincing evidence of a global increase in rates of all-cause anaphylaxis, driven largely by medication- and food-related anaphylaxis. There is no evidence of parallel increases in global all-cause anaphylaxis mortality, with surprisingly similar estimates for case-fatality rates at approximately 0.5% to 1% of fatal outcomes for hospitalizations due to anaphylaxis across several regions. Studying regional patterns of anaphylaxis to certain triggers have provided valuable insights into susceptibility and sensitizing events: for example, the link between the mAb cetuximab and allergy to mammalian meat. Likewise, data from published fatality registers can identify potentially modifiable risk factors that can be used to inform clinical practice, such as prevention of delayed epinephrine administration, correct posturing during anaphylaxis, special attention to populations at risk (such as the elderly on multiple medications), and use of venom immunotherapy in individuals at risk of insect-related anaphylaxis.

Idiopathic anaphylaxis yardstick: Practical recommendations for clinical practice

Anaphylaxis is considered idiopathic when there is no known trigger. The signs and symptoms of idiopathic anaphylaxis (IA) are identical to those of anaphylaxis because of a known cause and can include cutaneous, circulatory, respiratory, gastrointestinal, and neurologic symptoms. Idiopathic anaphylaxis can be a frustrating disease for patients and health care providers. Episodes are unpredictable, and differential diagnosis is challenging. Current anaphylaxis guidelines have little specific guidance regarding differential diagnosis and long-term management of IA. Therefore, the objective of the Idiopathic Anaphylaxis Yardstick is to use published data and the authors' combined clinical experience to provide practical recommendations for the diagnosis and management of patients with IA.