Children who experience severe allergic reactions are more likely to have a repeat, delayed anaphylactic reaction from the same allergic cause, depending on the severity of the initial reaction.
A study led at the Children's Hospital of Eastern Ontario (CHEO) Research Institute looked at the frequency and severity of biphasic allergic reactions.
From a sample size of 484 patient records, the incidence of biphasic reaction occurred in 15 percent of the study population, and two thirds occurred within six hours from the onset of the initial reaction.
At least half of the biphasic reactions were serious in nature, and required treatment with epinephrine.
The study unveiled that biphasic reactions were more likely to happen if the initial allergic reaction was severe or if it was not treated with epinephrine.
Furthermore, the anaphylaxis tended to be more severe when the administration of epinephrine was delayed.
The team identified five independent, evidence-based predictors of biphasic reactions in children, including: delay in presentation to the Emergency Department (or delay in epinephrine administration) of more than 90-minutes from the onset of the initial allergic reaction.
Second, wide pulse pressure at triage. Third, treatment of the initial allergic reaction with more than one dose of epinephrine.
Fourth, respiratory distress that requires administration of inhaled salbutamol in the Emergency Department. And the last, children between the ages of six to nine years old.
The study is published in Annals of Allergy, Asthma and Immunology.