Outcomes associated with prehospital epinephrine in adult and pediatric patients with anaphylaxis.

Background: Prompt epinephrine administration is important to improve outcomes in anaphylaxis.

Objective: To assess the impact of prehospital epinephrine on clinical outcomes of hospital admission, biphasic reactions, and emergency department (ED) length of stay (LOS) in a cohort of ED patients who had anaphylaxis including both children and adults.

Methods: We conducted a single-center prospective and retrospective cohort study of patients who had anaphylaxis from April 2008 to December 2022. Associations between prehospital epinephrine administration with biphasic reactions and ED LOS were assessed with univariable models and the association with ED disposition was assessed with both univariable and multivariable logistic regression.

Results: A total of 1107 patient visits were included for analysis. The median patient age was 29 (IQR: 14-50), 593 (53.6%) patients were of female sex, and 366 (33.1%) were younger than 18 years of age. Patients in the prehospital epinephrine group were also less likely to experience a biphasic reaction (5.4% vs 9.3%; odds ratio [OR] 0.56, 95% CI: 0.34-0.92) and had a decreased ED LOS (median 4.0 hours vs 4.7 hours). There was no difference in hospital admission between patients with and without prehospital epinephrine in both the univariable (19.5% vs 15.7%; OR 1.30, 95% CI: 0.94-1.79) and multivariable (adjusted OR 1.08, 95% CI: 0.71-1.64) models.

Conclusion: Prehospital epinephrine administration reduced the odds of a biphasic reaction and decreased ED LOS but did not reduce hospitalization in this cohort of ED patients who had anaphylaxis. Our findings suggest that timely administration of prehospital epinephrine is associated with improved patient outcomes.