Emergency Management of Anaphylaxis Due to an Unknown Trigger: An 8-Year Follow-Up Study in Canada.

Authors

Michelle Le
Sofianne Gabrielli
Ann Clarke
Harley Eisman
Judy Morris
Jocelyn Gravel
Edmond S Chan
Rod Lim, London Health Sciences Centre
Andrew O'Keefe
Greg Shand
Moshe Ben-Shoshan

Document Type

Article

Publication Date

4-2019

Journal

Journal of Allergy and Clinical Immunology in Practice

Volume

7

Issue

4

First Page

1166

Last Page

1173

URL with Digital Object Identifier

https://doi.org/10.1016/j.jaip.2018.11.015

Abstract

BACKGROUND:
Anaphylaxis due to unknown trigger (AUT) is anaphylaxis not explained by a proved or presumptive cause or stimulus at the time of the reaction. Research describing the management and follow-up of AUT is limited.

OBJECTIVE:
To assess and compare the demographic and clinical characteristics and the management of adult and pediatric AUT cases across Canada.

METHODS:
Participants were identified between 2011 and 2018 in emergency departments at 8 centers across Canada as part of the Cross-Canada Anaphylaxis Registry. A standardized form documenting the reaction and management in children and adults was completed. Patients were contacted for follow-up to determine assessment by an allergist.

RESULTS:
A total of 295 AUT cases (7.5%) were recruited among 3,922 cases of anaphylaxis. In the prehospital setting, children (adjusted odds ratio [aOR], 1.20; 95% CI, 1.05-1.37) and those with a known food allergy (aOR, 1.14; 95% CI, 1.02-1.28) were more likely to receive treatment with epinephrine. Children were also more likely to be assessed by an allergist after their reaction (aOR, 1.43; 95% CI, 1.13-1.81) and were more likely to have an identified trigger for their reaction (aOR, 1.35; 95% CI, 1.07-1.70). Among patients contacted for follow-up, food was identified as the cause of reaction in 11 of 76 patients. A new food allergy was diagnosed in 4 patients (2 children and 2 adults).

CONCLUSIONS:
Our findings highlight important differences between management and follow-up of adult and pediatric AUT cases. It is crucial to follow up all cases of AUT and establish appropriate treatment and management guidelines.