Anaphylaxis: preventative therapy may reduce recurrent episodes and hospital admissions in idiopathic cases

Clinical bottom line (level 4)

  1. Most patients with idiopathic anaphylaxis on treatment were in remission.
  2. Few patients were admitted to hospital on treatment.
Krasnick et al: Allergy 1996; 51: 724-731
Expires November 2004

The study

Inception cohort study with objective outcomes, adjusted for confounding factors, validated in an independent set of patients.

Setting: allergy clinic, university hospital, USA

225 patients (aged 10 to 68; mean 39, 56% female) with idiopathic anaphylaxis

Excluded if
  • non-compliant
  • no longer considered to have idiopathic anaphylaxis
    •  
All patients were given self-administered epinephrine. Patients were told to take the epinephrine if an acute episode occurred, as well as 60 mg prednisone, an antihistamine (diphenhydramine 60 gm, hydroxyzine 25 mg, or chlorpheniramine 4 mg) by mouth), and to proceed to the nearest emergency department. Patients with frequent episodes took prophylactic prednisone 60-100 mg daily for 1 week or until signs and symptoms are controlled: then convert to alternate-day prednisone, 60-100 mg, cautiously tapering by no more than 5-10 mg per month. Continuous antihistamine and sympathomimetic agents.

27% followed for 3 to 27 years
Outcomes studied:

in remission no episodes of idiopathic anaphylaxis requiring prednisone or epinephrine within previous year

hospital admission with anaphylaxis


The evidence

outcome time to outcome number of patients/total number %
(95% CI)
in remission 3 to 27 years 49/61 80%
(70% to 90%)
hospital admission with anaphylaxis 3 to 27 years 3/61 4.9%
(0.0% to 10%)

Comments

  1. The substantial loss to follow-up makes these results far less certain.
  2. Hospital admissions (35 to 3) and emergency room attendances (165 to 51) fell on starting the treatment regimen.

Citation

  1. Krasnick J, Patterson R, Harris KE, et al: idiopathic anaphylaxis: long-term follow-up, cost and outlook. Allergy 1996; 51: 724-731
Contributor: Mike Bennett & Chris Ball, November 1999
Reviewer: Arturo Marti-Carvajal

Clinical Question.
Patient with idiopathic anaphylaxis
Intervention or Exposure acute episode
Outcome remission or hospitalisation