Outcome of prophylactic therapy for idiopathic anaphylaxis

To determine the efficacy of a prophylactic regimen (prednisone, H1 blockade, and sympathomimetic amine therapy) in patients with idiopathic anaphylaxis.

Clinical trial before and after treatment.

Referral-based allergy clinic at a major medical center.

Fifty-three patients with a history compatible with idiopathic anaphylaxis for at least 6 months before presentation to the allergy service and with subsequent management by the service for at least 6 months.

Patients with frequent life-threatening symptoms were treated with a prophylactic regimen. Patients with infrequent episodes of idiopathic anaphylaxis were only treated acutely for each episode of anaphylaxis.

The results favored prophylactic treatment with prednisone for patients who were classified as generalized-frequent in the clinical outcome measures of frequency (per patient per year) of episodes (mean before treatment, 7.31 +/- 6.46; after treatment, 3.61 +/- 4.73; P less than 0.02) and emergency room visits (mean before treatment, 1.94 +/- 3.42; after treatment, 0.21 +/- 0.44; P less than 0.005) and for patients classified as angioedema-frequent in the frequency of episodes (mean before treatment, 14.93 +/- 15.89; after treatment, 2.58 +/- 2.18; P less than 0.003) and emergency room visits (mean before treatment, 0.76 +/- 1.01; after treatment, 0.07 +/- 0.11; P less than 0.025). No statistically significant difference was found for patients classified as generalized-infrequent in the frequency of episodes (mean before treatment, 2.01 +/- 1.30; after treatment, 1.36 +/- 1.79) or of the emergency room visits (mean before treatment, 0.56 +/- 0.71; after treatment, 0.32 +/- 0.75) or for patients classified as angioedema-infrequent in the frequency of episodes (mean before treatment, 1.94 +/- 1.55; after treatment, 2.03 +/- 2.16) or of emergency room visits (mean before treatment, 0.27 +/- 0.44; after treatment, 0.37 +/- 0.59).

Prophylactic treatment with prednisone and H1 antihistamines with or without sympathomimetic amines improves clinical outcome in patients who are classified as idiopathic anaphylaxis-angioedema frequent and idiopathic anaphylaxis-generalized frequent.