Epinephrine in Severe Allergic Reactions: The European Anaphylaxis Register

Background: Current guidelines recommend intramuscular administration of epinephrine as the first-line drug for the emergency treatment of severe allergic reactions (anaphylaxis), but no randomized trial evidence supports this consensus.

Objective: We aimed to assess anaphylaxis treatment practices over 10 years, covering several European regions, all allergen sources, and all age groups.

Methods: The European Anaphylaxis Register tracks elicitors, symptoms, emergency treatment, diagnostic workups, and long-term counseling for anaphylaxis incidents through web-based data entry from tertiary allergy specialists, covering information from the emergency respondent, patient, tertiary referral, and laboratory/clinical test results.

Results: We analyzed 10,184 anaphylaxis incidents. In total, 27.1% of patients treated by a health professional received epinephrine and, in total, 10.5% received a second dose. Successful administration was less frequent in German-speaking countries (minimum 19.6%) than in Greece, France, and Spain (maximum 66.7%). Over the last decade, epinephrine administration from a health professional almost doubled to reach 30.6% in 2015-2017, half of which was applied intramuscularly. A total of 14.7% of lay- or self-treated cases were treated with an autoinjector. Of those without treatment, 22.4% carried a device for administration. No change in successful administration by lay emergency respondents was found over the last 10 years. Of the reaction and patient characteristics analyzed, only clinical severity considerably influenced the likelihood of receiving epinephrine, with 66.9% of successful administrations in near-fatal (grade IV) reactions.

Conclusions: Despite clear recommendations, only a small proportion of anaphylaxis incidents are treated with epinephrine. We demonstrated a slight increase in treated patients when handled by professionals, but stagnation in lay- or self-treated anaphylaxis. The reaction circumstances, the respondent's professional background, and patient characteristics did not explain which reactions were treated.