D1.14 - Biphasic, Refractory, and Persistent Anaphylaxis in Children

In November 2020, a Delphi consensus report refined anaphylaxis phenotypes as biphasic, refractory, and persistent anaphylaxis (BA, RA, and PA). To date, no study in either pediatric or adult populations has comprehensively evaluated the full spectrum of anaphylaxis phenotypes as outlined in this consensus. The primary aim of this study was to assess and compare the anaphylaxis phenotypes in children.

Patients aged ≤18 years who were diagnosed with anaphylaxis and followed at our institution between January 2010 and January 2025 were screened for this study. All anaphylaxis cases were stratified as BA, RA, PA, and other types. These three phenotypes were analyzed as one group versus other cases, and separately to assess differences in demographics, comorbidities, triggers, clinical features, treatments, and outcomes.

A total of 393 patients and 529 anaphylaxis episodes were reviewed. Twenty-six (6.6%) of all anaphylaxis cases were classified as biphasic (3.5%), refractory (1.5%), or persistent anaphylaxis (1.5%). The median onset time for BA was 4 hours (1-24 hours) and the median duration for PA was 4 hours (4-6 hours). These phenotypes were more common in older children and were associated with increased cardiovascular manifestations, greater severity, and higher use of systemic corticosteroid (p<0.001). They did not differ significantly by gender, comorbidities, family history of atopy, timing or location of the anaphylaxis, or number of episodes. Drugs, followed by venoms, were more frequent triggers in these phenotypes, whereas food was significantly more common in other cases (p<0.05). IM adrenaline was administered in 69.2% of BA, RA, and PA phenotypes and 52.3% of other anaphylaxis phenotypes, with no significant difference (p>0.05).

BA, RA, and PA are rare, more frequently drug- or venom-induced anaphylaxis phenotypes seen at older ages, with ongoing gaps in proper IM adrenaline use.