1. Home>
2. Specialties>
3. General Medicine>
4. Summary and Comment

Can We Prevent Anaphylactic Reactions to Contrast Media?

Given how infrequent severe reactions are, pretreatment does not seem worthwhile.

Although the use of nonionic contrast media has resulted in a decrease in adverse reactions, many medical centers and organizations still recommend pretreatment regimens to prevent allergic reactions. This systematic review suggests that such a strategy has a low yield.

Investigators found nine randomized trials, involving 10,011 adults, in which pretreatment was compared with either placebo or no treatment. Pretreatment regimens included corticosteroids, H₁ antihistamines, and an H₁-H₂ combination. In two trials, the incidence of laryngeal edema was reduced from 1.4% to 0.4% with steroid premedication. In two trials, a composite adverse outcome measure (shock, bronchospasm, or laryngospasm) was reduced from 0.9% to 0.2%. In one trial, angioedema was reduced from 4.1% to 0.5%. There were no reports of death, cardiopulmonary resuscitation, or prolonged hospital stay. Based on the data, to prevent one potentially life-threatening reaction would require pretreatment of 100 to 150 patients with steroids.

Comment: This review considered a variety of adverse reactions, including many that are not truly allergic. While it showed that steroid pretreatment had a significant effect on some of the reactions, it also showed that such reactions are infrequent. The study's authors conclude that given the rarity of severe reactions, and the absence of death or need for cardiopulmonary resuscitation in these studies, such pretreatment is not worthwhile. At the time of publication, the full text of the original article was available free of charge.

— Keith I. Marton, MD

Published in Journal Watch General Medicine November 16, 2006

Citation(s):

Tramèr MR et al. Pharmacological prevention of serious anaphylactic reactions due to iodinated contrast media: Systematic review. BMJ 2006 Sep 30; 333:675-8.

• Original article (Subscription may be required)
• Medline abstract (Free)

Dawson P. Adverse reactions to intravascular contrast agents. BMJ 2006 Sep 30; 333:663-4.

• Original article (Subscription may be required)
• Medline abstract (Free)