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Research shows that most children presenting to the emergency department with an acute allergic reaction requiring epinephrine can probably be safely discharged after 2 hours.

Most children presenting to the emergency department (ED) with an acute allergic reaction requiring epinephrine can probably be safely discharged after 2 hours of observation, and a 4-hour period may be adequate for children with cardiovascular involvement who appear well, according to a study published in The Lancet Child & Adolescent Health.

“Children presenting to the emergency department with anaphylaxis typically receive at least one dose of epinephrine and are observed in the emergency department or monitored for recurrent (biphasic anaphylaxis) or persistent symptoms on hospital wards for variable durations before discharge is considered safe,” wrote corresponding author Timothy E. Dribin, MD, of Cincinnati Children’s Hospital Medical Center, and study coauthors. “We aimed to calculate the incidence rate and timing of repeat epinephrine dosing to determine the observation threshold at which the cumulative incidence of repeat epinephrine was less than 2% for every 1 h increase in observation time.”

Large Multicenter Cohort

In the largest retrospective analysis to date of pediatric anaphylaxis in North America, the research team reviewed health record data across 31 EDs from 2016 to 2019 for 5,641 pediatric patients with an acute allergic reaction requiring intramuscular, subcutaneous, or IV epinephrine; 1,070 had no respiratory or cardiovascular involvement, 4,076 had respiratory but no cardiovascular involvement, and 495 had cardiovascular involvement. The patients ranged in age from 6 months to 17 years (median age, 7.9 years); 43.9% were female and 22.0% identified as Hispanic.

The authors calculated the interval from first to final epinephrine administration and stratified outcomes by respiratory and cardiovascular involvement.

Minimal Need for Repeat Epinephrine

According to the authors, only 4.7% of the patients required an additional epinephrine dose after 2 hours. The incidence fell to 1.9% at 4 hours after the initial dose, 1.1% at 6 hours, and 0.8% at 8 hours. Kaplan-Meier modelling showed that once 115 minutes had elapsed, the cumulative risk of another dose rose by less than 2% for every additional hour of monitoring.

Risk thresholds differed by presentation, the researchers noted. Children without respiratory or cardiovascular involvement reached the less-than-2% threshold at 105 minutes; those with respiratory involvement, at 109 minutes; and those with cardiovascular involvement, at 161 minutes.

“These findings suggest that 5378 (95·3%) patients in our cohort would have been safely discharged 2 h after receiving the first epinephrine dose and that 5532 (98·1%) patients would have been safely discharged 4 h after the first epinephrine dose,” the authors wrote.

Instilling Clinician Confidence & Empowering Parental Choices

These data challenge the long-standing habit of extended ward monitoring to capture biphasic reactions.

“Pediatric emergency departments can get crowded quite quickly, especially during winter infection season. We need to ensure efficient throughput to allow us to provide access to as many patients as we can,” said David Schnadower, MD, MPH, of Cincinnati Children’s Hospital Medical Center in a news release. “An important value of this study is that it was large enough that the results can give clinicians confidence that discharging patients showing no concerning symptoms in less than two hours is going to be safe for most children.”

Dr. Dribin added, “I think the bigger impact would be for the patients and families…parents being able to go back to work quicker, children missing less school. This data allows clinicians to make decisions about observation based on their risk tolerance and that of the patient and the family. Some families might feel risk-averse and want to stay a little longer. Others might have another auto injector, and they feel comfortable managing at home. Having that choice is really empowering.”