title: Epidemiology and clinical predictors of biphasic reactions in children with anaphylaxis.
abstract: BACKGROUND
  Epidemiologic data regarding biphasic reactions in children with anaphylaxis are sparse.
  
  
  OBJECTIVE
  To investigate the incidence and clinical predictors of biphasic reactions in children presenting to the emergency department (ED) with anaphylaxis.
  
  
  METHODS
  A health records review of ED visits at 2 large Canadian academic pediatric EDs was conducted. All visits that satisfied anaphylaxis diagnostic criteria of the National Institute of Allergy and Infectious Diseases and the Food Allergy and Anaphylaxis Network were included. Predictors of biphasic reaction were analyzed using univariate and multiple logistic regression analyses.
  
  
  RESULTS
  Of 1,749 ED records reviewed, 484 visits met the study inclusion criteria. Seventy-one patients (14.7%) developed biphasic reactions. The median age was 6 years (interquartile range 2.7-10.1) and 51 (71.8%) were boys. Forty-nine of the 71 (69%) delayed reactions involved respiratory and/or cardiovascular manifestations and 35 (49%) were treated with epinephrine. Five independent predictors for biphasic reactions were found: age 6 to 9 years (odds ratio [OR] 3.60, 95% confidence interval [CI] 1.5-8.58), delay in presentation to the ED longer than 90 minutes after the onset of the initial reaction (OR 2.58, 95% CI 1.47-4.53), wide pulse pressure at triage (OR 2.92, 95% CI 1.69-5.04), treatment of the initial reaction with more than 1 dose of epinephrine (OR 2.7, 95% CI 1.12-6.55), and administration of inhaled β-agonists in the ED (OR 2.39, 95% CI 1.24-4.62).
  
  
  CONCLUSIONS
  Biphasic reactions seem to be associated with the severity of the initial anaphylactic reactions. We identified clinical predictors that could ultimately be used to identify patients who would benefit from prolonged ED monitoring and enable better utilization of ED resources.
authors.affiliation: Department of Pediatrics and Emergency Medicine, University of Ottawa, Ottawa, Ontario, Canada; Department of Clinical Epidemiology, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada. Electronic address: walqurashi@cheo.on.ca.
authors.forename: Waleed
authors.initials: W
authors.lastname: Alqurashi
authors.affiliation: Department of Clinical Epidemiology, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Department of Emergency Medicine, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Ian
authors.initials: I
authors.lastname: Stiell
authors.affiliation: Memorial University and Eastern Health, St John's, Newfoundland, Canada.
authors.forename: Kevin
authors.initials: K
authors.lastname: Chan
authors.affiliation: Department of Pediatrics and Emergency Medicine, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Gina
authors.initials: G
authors.lastname: Neto
authors.affiliation: Department of Clinical Epidemiology, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada.
authors.forename: Abdulaziz
authors.initials: A
authors.lastname: Alsadoon
authors.affiliation: Department of Clinical Epidemiology, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: George
authors.initials: G
authors.lastname: Wells
mesh_terms: D000318:Adrenergic beta-Agonists / Q000627:therapeutic use; D000707:Anaphylaxis / Q000188:drug therapy / Q000453:epidemiology* / Q000276:immunology*; D002648:Child; D002675:Child, Preschool; D004636:Emergency Service, Hospital; D004837:Epinephrine / Q000627:therapeutic use; D005260:Female; D006801:Humans; D008297:Male; D012189:Retrospective Studies; D012307:Risk Factors; D016896:Treatment Outcome
chemical_list: D000318:Adrenergic beta-Agonists; D004837:Epinephrine