Anaphylaxis: Early Epinephrine Tied to Fewer Overall Doses

Karen Blum

April 22, 2016

Although anaphylaxis accounts for an increasing percentage of all pediatric emergency department (ED) visits, early use of epinephrine before ED arrival is associated with a lower likelihood of requiring multiple doses of epinephrine in the ED, Canadian researchers report.

Epinephrine use before ED arrival was the only factor associated with a reduced risk for multiple ED epinephrine doses (odds ratio [OR], 0.2; 95% confidence interval [CI], 0.0 - 0.6) among pediatric patients with anaphylaxis, write Elana Hochstadter, MD, from the Department of Pediatric Emergency Medicine at the University of Toronto's Hospital for Sick Children, Ontario, Canada, and colleagues. The researchers reviewed 965 anaphylaxis cases from Montreal Children's Hospital that were included in the Cross-Canada Anaphylaxis Registry (C-CARE), which tracks individuals presenting to EDs or emergency medical services with the condition.

More than 25% of moderate/severe anaphylaxis cases did not receive epinephrine inside or outside the hospital, and "[o]nly 50.7% (95% CI, 45.9-55.4) of those who had an epinephrine autoinjector used it before arrival to the ED," the authors write in a letter to the editor published online April 20 in the Journal of Allergy and Clinical Immunology.

Factors associated with an increased likelihood of receiving multiple doses of epinephrine in the ED were older age (OR, 1.1; 95% CI, 1.0 - 1.2), a severe reaction (OR, 17.3; 95% CI, 6.1 - 49.2), and anaphylaxis cases triggered by peanuts (OR, 2.9; 95% CI, 1.1 - 8.5), tree nuts (OR, 7.2; 95% CI, 2.6 - 20.2), and milk (OR, 5.2; 95% CI, 1.4 - 20.0).

The percentage of anaphylaxis cases among all ED visits more than doubled from April 2011 to April 2015, going from 0.20% (95% CI, 0.18% - 0.24%) to 0.41% (95% CI, 0.36% - 0.45%), with the largest annual increase seen between 2013-2014 and 2014-2015 (0.11%). The median age of patients was 5.8 years. Almost half of patients reported a known food allergy, and asthma and eczema were reported in almost 20% of patients. Most cases (85.3%; 95% CI, 82.0% - 87.5%) were referred to an allergist after the ED visit or already had consulted with an allergist.

Food was the most common trigger of anaphylaxis in the study, responsible for 80% of cases, with peanut responsible for 22.2% (95% CI, 19.4% - 25.3%). Most reactions were moderate in severity; asthma (OR, 2.3; 95% CI, 1.2 - 4.5) and eczema (OR, 2.1; 95% CI, 1.1 - 4.2) were associated with severe reactions.

Although the results are from just one center, "they suggest a worrisome increase in anaphylaxis rate that is consistent with the worldwide reported increase," the authors note. "Both our study and US studies reveal that a higher percentage of pediatric ED visits are due to anaphylaxis in North America compared with European centers. This likely reflects differences in the prevalence of food allergies between North America and Europe."

The study had several limitations, including using data from only one pediatric hospital and the fact that researchers were unable to determine whether older patients received more doses of epinephrine because it was appropriate for their size. In addition, data were unavailable for the specific time interval between prehospital epinephrine administration and ED arrival.

The study was funded by the Allergy, Genes and Environment Network Centres of Excellence (AllerGen NCE), Health Canada, and Sanofi. The authors have disclosed no relevant financial relationships.

J Allergy Clin Immunol. Published online April 20, 2016. Abstract

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