Anaphylaxis appears to be heterogeneous with regards to patients’ characteristics, clinical manifestations, triggers, and severity.

We set out to define anaphylaxis phenotypes using a non-supervised cluster analysis in children experiencing anaphylaxis.

Characteristics of children (<18y) admitted for anaphylaxis to emergency care units in three French regions were recorded and 23 of these variables were analyzed in a clustering analysis.

(See Fig. 1) Two hundre and twenty two (male: 62%, mean age: 7.9 y; SD: 5.1) children were included. Two anaphylaxis clusters have been described. Cluster 1, “Food (nuts) severe anaphylaxis in highly atopic children” (n=56, 25%): all children had food-induced anaphylaxis, most often induced by peanut (38%) and nuts (36%), and a previous food allergy to the same trigger (89%). These children had allergic comorbidities (multiple food allergy, 77%; asthma, 63%; atopic dermatitis, 36%) and had more severe anaphylaxis reactions (Ring score 3–4, 45%; adrenaline injection, 46%; hospital admission, 36%). Cluster 2, “Mild anaphylaxis with various triggers and few atopic comorbidities” (n=168, 75%): these children were younger (p=0.039), had less frequent allergic disease (asthma, 31%; food allergy, 16%; atopic dermatitis, 17%), with various triggers (food, 68%; drugs, 10%; insect venom, 7%) and less severe reactions (Ring 2, 78%; adrenaline injection, 26%; hospital admission, 20%).

We confirm the heterogeneity of anaphylaxis in children. Children with allergic comorbidities and food triggers (nuts) are at risk of more severe anaphylaxis reactions as compared to children with less allergic disease and other triggers than food. Larger studies are required to confirm these anaphylaxis phenotypes in children.