Refractory Anaphylaxis: Data From the European Anaphylaxis Registry

Area of Science:

• Immunology
• Allergy and Clinical Immunology
• Pharmacology

Background:

• Refractory anaphylaxis, defined by unresponsiveness to at least two adrenaline doses, is a rare, severe hypersensitivity reaction with limited data.
• Understanding its definition, prevalence, and risk factors is crucial for improving patient outcomes.

Purpose of the Study:

• To define and analyze the characteristics of refractory anaphylaxis.
• To compare refractory cases with severe anaphylaxis to identify distinct risk factors and triggers.
• To evaluate treatment patterns and outcomes in refractory anaphylaxis.

Main Methods:

• Utilized data from the European Anaphylaxis Registry (11,596 cases).
• Identified 42 refractory anaphylaxis cases and compared them to 4,820 severe anaphylaxis control cases.
• Analyzed triggers, clinical settings, treatment administration (intramuscular vs. intravenous adrenaline), and mortality rates.

Main Results:

• Drugs were more frequent triggers in refractory anaphylaxis (50%) compared to severe cases (19.7%).
• Refractory cases predominantly occurred in a perioperative setting (45.2%) and involved bee stings more than wasp stings.
• Intravenous adrenaline was more common in refractory cases, and second-line treatments were not utilized; mortality was significantly higher (26.2% vs. 0.353%).

Conclusions:

• Refractory anaphylaxis is strongly associated with drug-induced anaphylaxis, particularly with intravenous allergen administration.
• Perioperative anaphylaxis frequently becomes refractory despite adrenaline use, necessitating further investigation into recognition delays or mast cell activation.
• The underutilization of second-line medications like methylene blue or dopamine warrants further study, as their use may improve outcomes in severe refractory anaphylaxis.