Patterns of epinephrine prescribing at discharge and length of stay for adult anaphylaxis in U.S. emergency departments

Background: Anaphylaxis is a life-threatening allergic reaction that requires prompt epinephrine and post-treatment management. Guidelines recommend prescribing epinephrine at discharge from the emergency department (ED), yet results of studies show lower-than-recommended prescribing rates and variable ED lengths of stay (LOS). Large-scale analyses of adult anaphylaxis care in U.S. EDs remain limited. Objective: The objective was to estimate the proportion of adults discharged from U.S. EDs with an epinephrine prescription, characterize ED LOS, and identify predictors of these outcomes. Methods: We analyzed 2013‐2015 and 2018‐2022 National Hospital Ambulatory Medical Care Survey‐ED visits for adults ages ≥ 18 years diagnosed with anaphylaxis who were discharged home. Outcomes were (1) epinephrine prescription at discharge and (2) ED LOS < 4 hours. Patients who arrived by emergency medical services (EMS) were excluded for LOS analysis. Multivariable log-binomial regression estimated risk ratios (RR) between outcomes and clinical predictors. Results: Among 609 ED visits, 14% resulted in an epinephrine prescription at discharge (95% confidence interval [CI], 10%‐18%). The median (interquartile range) LOS was 138 minutes (80‐199 minutes), with 83% discharged within 4 hours (95% CI, 78%‐87%). Older adults (≥42 years) and Hispanic patients were less likely to receive an epinephrine prescription (RR 0.47 [95% CI, 0.25‐0.90]; RR 0.34 [95% CI, 0.12‐0.95], respectively). Rural visits were more likely to have LOS < 4 hours (RR 1.12 [95% CI, 1.02‐1.23]). Conclusion: Epinephrine prescribing at discharge was infrequent across the full cohort, whereas ED LOS was typically brief among the patients who did not arrive by EMS. Older adults and Hispanic patients were less likely to receive epinephrine, and rural visits had shorter LOS. These findings highlight potential disparities in discharge prescribing and ED management of adult anaphylaxis in U.S. EDs.