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How Often Does Anaphylaxis Require Redosing of Epinephrine?

May 12, 2021

Written by Andy Hogan

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Roughly 1 in 10 cases of anaphylaxis evaluated by a healthcare professional are treated with at least 2 doses of epinephrine.

Why does this matter?
In the latest anaphylaxis guidelines, the most important take-home point is to use epinephrine. A small but significant percentage of patients experiencing anaphylaxis require redosing of epinephrine for persistent or recurrent (biphasic) symptoms. For this reason, the FDA and other regulatory agencies recommend at-risk patients always carry two epinephrine autoinjectors (EAI), and we should consider prescribing two EAIs when discharging these patients from the ED. How often do patients need a redose?

Episode II: The Epipen Strikes Back
This systematic review and meta-analysis examined more than 36,000 anaphylaxis events across multiple public, outpatient, and acute care settings. Meta-analysis revealed that 7.1-12.2% of episodes assessed by a healthcare professional received >1 dose of epinephrine. Despite substantial heterogeneity among the 86 studies analyzed, this figure did not significantly change after robust sensitivity analysis. Due to source data limitations, this study could not determine how frequently epinephrine was redosed for persistent symptoms versus true biphasic reactions. Furthermore, the analysis was unable to identify specific risk factors for epinephrine redosing.

Despite these limitations, the study provides a ballpark estimate of 10% for the likelihood a patient will require more than one epinephrine dose for anaphylaxis. This underscores the importance of patient reassessment during treatment of anaphylaxis and offers some support for prescribing EAIs in pairs when patients are discharged. This practice pattern, however, might unintentionally lead patients to delay seeking emergent care prolonging self-treatment of a life-threatening condition. Purchasing a second EAI may also be financially burdensome for many at-risk patients. Emergency providers should consider all of these factors during discharge planning.

Use of multiple epinephrine doses in anaphylaxis: A systematic review and meta-analysis. J Allergy Clin Immunol. 2021 Apr 13:S0091-6749(21)00566-2. doi: 10.1016/j.jaci.2021.03.042. Epub ahead of print.

What are your thoughts?