A new study has identified a more accurate way to diagnose anaphylaxis in children. The research, spanning ten years, found that a ratio of serum acute tryptase to serum baseline tryptase above 1.74 demonstrated superior diagnostic performance compared to the current consensus formula. The existing formula relies on serum acute tryptase exceeding a personalized cutoff value. The new ratio correctly identified over two-thirds of true anaphylaxis cases while effectively ruling out the majority of false positives in children with suspected anaphylaxis.

The study, published in the Journal of Allergy and Clinical Immunology: Global, reviewed the medical records of 315 children admitted to the emergency department between January 2011 and December 2020. The children, with a median age of 7.8 years (56.2% boys), were assessed for the diagnostic performance of serum tryptase measurements. Anaphylaxis was confirmed in children exhibiting at least one extracutaneous systemic symptom along with evidence of systemic mast cell activation or allergic sensitization to a trigger allergen.

Of the 315 children, 175 were diagnosed with anaphylaxis, forming the anaphylaxis group, while the remaining 142 served as the control group. Researchers then compared the diagnostic performance of the consensus formula with five alternative tryptase interpretation algorithms.

Key Findings

The study revealed that food allergens were responsible for 82% of anaphylaxis reactions.Legumes, seeds, and nuts triggered 36% of cases, followed by cow’s milk proteins in 28% of cases. Epinephrine, a common treatment for anaphylaxis, was administered to 96 children with suspected anaphylaxis (30.3%), including 14 children initially misdiagnosed due to cardiovascular involvement and a history of allergen exposure.

“Our study underlines the need for better implementation of both sAT [serum acute tryptase] and sBT [serum baseline tryptase] measurements.”

The ratio of serum acute tryptase to serum baseline tryptase exhibited optimal diagnostic performance, with an area under the curve of 0.84,a sensitivity of 66.7%, and a specificity of 90% at a threshold of 1.74.This outperformed the current consensus formula,which has a sensitivity of 62.2% and a specificity of 80%.

Implications for Practice

According to the study authors, including corresponding author Moïse Michel, PhD, with the Nîmes University Hospital, Nîmes, France, the findings highlight the necessity for improved implementation of serum acute tryptase (sAT) and serum baseline tryptase (sBT) measurements at appropriate sampling times in pediatric emergency departments. The research contributes to the ongoing discussion regarding the optimal interpretation of pediatric dynamic tryptase.

The authors also noted the study’s limitations, including its retrospective design and the absence of grade 4 anaphylaxis cases, which limited the evaluation of tryptase measurement performance in severe cases.