Management of anaphylaxis in a Swiss university hospital emergency department: a retrospective observational study assessing adherence to epinephrine administration

Summary

INTRODUCTION: Anaphylaxis is a severe and potentially life-threatening allergic reaction, most frequently triggered by food, medication and insect venom. Its diagnosis is challenging due to the absence of pathognomonic signs and instead relies on the sudden onset of multisystem symptoms. Although international guidelines recommend intramuscular (i.m.) epinephrine as the first-line treatment, several studies suggest that it remains underused, with antihistamines and corticosteroids still frequently administered. This highlights a persistent gap between guideline recommendations and real-world clinical practice.

OBJECTIVE: To assess use of i.m. epinephrine in patients with anaphylaxis and to identify factors associated with its administration.

METHODS: We conducted a single-site, retrospective observational study of all consecutive patients presenting to the emergency department (ED) of a Swiss university hospital who were triaged under the “allergy” category between 1 January 2022 and 31 December 2023. Among these patients (n = 915), 277 met the World Allergy Organization (WAO) criteria for anaphylaxis, 553 were identified as non-anaphylactic immediate allergic reactions and 85 were excluded due to missing data or missed triage. For the 915 patients, data on the medical history, vital signs, clinical examination, management and the discharge summary were extracted from the hospital information system for analysis. Cases were classified as anaphylactic or non-anaphylactic immediate allergic reactions, based on the WAO systemic allergic reaction grading system. Treatments received in the ED were then analysed. The primary outcome was the proportion of patients with anaphylaxis who received i.m. epinephrine as first-line treatment. The secondary outcome was the identification of clinical and demographic factors associated with its administration.

RESULTS: Among patients meeting the WAO criteria for anaphylaxis, only 30.1% received i.m. epinephrine. Antihistamines and/or corticosteroids, despite being regarded as second-line treatments, were administered without epinephrine in 39.4% of cases. The administration of epinephrine was positively associated with older age, respiratory or cardiovascular symptoms, elevated heart rate and reduced systolic blood pressure. In contrast, it was less likely in females and in those presenting anaphylaxis with mucocutaneous symptoms. Gastrointestinal symptoms were not significantly associated with the likelihood of receiving i.m. epinephrine.

CONCLUSION: Despite clear guideline recommendations, the use of i.m. epinephrine in anaphylaxis remains suboptimal, with frequent reliance on second-line therapies. Female sex was independently associated with underuse, highlighting a potential sex bias. In contrast, haemodynamic instability and respiratory or ear-nose-throat involvement increased the likelihood of appropriate treatment.