Anaphylaxis: a biphasic response could occur

Clinical bottom line (level 4)

  1. One in sixteen patients with an episode of anaphylaxis had a recurrent episode within 24 hours without further exposure to the allergen.
Douglas et al: Journal of Allergy and Clinical Immunology 1994; 93: 977-985
Expires November 2004

The study

Case series with unblinded, unobjective outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: army medical centre, USA

94 patients (aged 6 months to 81 years, 61% male) 59 inpatients admitted with anaphylaxis and 35 outpatients with 44 episodes of anaphylaxis following allergy immunotherapy injections


?100% followed for 12 to 24 hours
Outcomes studied:
  • biphasic anaphylaxis recurrent episode without re-exposure to allergen

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)    		 NNF
    (95% CI)
    biphasic anaphylaxis 12 to 24 hours 6/94 6.4%
    (1.4% to 11%)    		 16
    (9 to 69)

    Comments

    1. Although the utility of corticosteroids for preventing or reducing severity of biphasic reaction has not been resolved, corticosteroid administration is recommended.
    2. Risk for biphasic reaction, whether due to immunologic factors or waning pharmacologic effects on ongoing mediator release, cannot be reliably predicted based on presentation or demographic features.

    Citation

    1. Douglas DM, Sukenick E, Andrade WP, et al: biphasic systemic anaphylaxis: an inpatient and outpatient study. Journal of Allergy and Clinical Immunology 1994; 93: 977-985
    Search Terms:
    Contributor: Mike Bennett and Chris Ball, November 1999
    Reviewer: David Lang

    Clinical Question.
    Patient anaphylaxis
    Intervention or Exposure
    Outcome further episode within 24 hours