Tree nut-induced anaphylaxis in Canadian emergency departments: Rate, clinical characteristics, and management.

Background: Data are sparse regarding tree nut-induced anaphylaxis (TNA).

Objective: To characterize rate, clinical characteristics, and management of TNA in children (0-17 years old) across Canada and evaluate factors associated with severe reactions and epinephrine use.

Methods: Between April 2011 and May 2020, data were collected on children presenting to 5 emergency departments in Canada. Multivariate logistic analysis was used to evaluate factors associated with severe reactions (stridor, cyanosis, circulatory collapse, or hypoxia) and epinephrine use.

Results: Among 3096 cases of anaphylaxis, 540 (17%) were induced by tree nut. The median age was 5.2 (interquartile range, 2.5-9.5) years and 65.4% were of male sex. Among all reactions, 7.0% were severe. The major tree nuts accounting for anaphylaxis were cashew (32.8%), hazelnut (20.0%), and walnut (11.5%). Cashew-induced anaphylaxis was more common in British Columbia (14.0% difference [95% confidence interval (CI), 1.6-27.6]) vs Ontario and Quebec, whereas pistachio-induced anaphylaxis was more common in Ontario and Quebec (6.3% difference [95% CI, 0.5-12.2]). Prehospital and emergency department intramuscular epinephrine administration was documented in only 35.2% and 52.4% of cases, respectively. Severe reactions were more likely among of male sex (adjusted odds ratio [aOR], 1.05 [95% CI, 1.01-1.10]), older children (aOR, 1.00 [95% CI, 1.00-1.01]), and in reactions triggered by macadamia (aOR, 1.27 [95% CI, 1.03-1.57]).

Conclusion: Different TNA patterns in Canada may be because of differences in lifestyle (higher prevalence of Asian ethnicity in British Columbia vs Arabic ethnicity in Ontario and Quebec). Intramuscular epinephrine underutilization urges for epinephrine autoinjector stocking in schools and restaurants, patient education, and consistent policies across Canada.