Anaphylaxis: severe anaphylaxis was rare

Clinical bottom line (level 4)

  1. Severe anaphylactic reactions were rare.
  2. A quarter of patients had a history of allergy.
Stewart and Evan: Quarterly Journal of Medicine 1996; 89: 859-864
Expires November 2004

The study

Case series with ?objective ?blinded outcomes, not adjusted for confounding factors, not validated in an independent set of patients.

Setting: emergency department, university hospital, UK

55000 patients (aged ?, ?% male) attending an emergency department



Outcomes studied:
  • severe anaphylaxis with loss of consciousness or fainting
  • generalised allergic reaction with dyspnoea, asthma, angioedema and/or urticaria
  • reactions with hypotension and/or respiratory difficulty

    • The evidence

    outcome time to outcome number of patients/total number %
    (95% CI)    		 NNF
    (95% CI)
    severe anaphylaxis ? 9/55000 0.016%
    (0.0057% to 0.027%)    		 6100
    (3700 to 18000)
    generalised allergic reaction ? 15/55000 0.027%
    (0.014% to 0.041%)    		 3700
    (2400 to 7400)
    reactions with hypotension and/or respiratory difficulty ? 24/55000 0.044%
    (0.026% to 0.061%)    		 2300
    (1600 to 3800)

    Comments

    1. Two separate study periods yielded different incidence rates, possibly due to altered methods of case identification.
    2. The probable cause was identified from record inspection - 8/33 patients (24%: 95% CI: 10% to 39%) gave a history of a previous allergic reaction.

    Citation

    1. Stewart AG, and Evan PW: the incidence, aetiology and management of anaphylaxis presenting to an Accident and Emergency department. Quarterly Journal of Medicine 1996; 89: 859-864
    Search Terms: ?
    Contributor: Mike Bennett and Chris Ball, November 1999
    Reviewer: Chris Ball

    Clinical Question.
    Patient attending emergency department
    Intervention or Exposure prevalence
    Outcome anaphylaxis