International Study of Severe Anaphylaxis

Objectives

To evaluate the role of drugs and other factors in the etiology of anaphylaxis among hospital patients, with emphasis on the comparative effects of analgesics.

Methods

Cases of anaphylaxis and controls were enrolled until December 1995 in three hospitals in Barcelona, Spain, and four hospitals in Bombay and Pune, India, and until March 1995 in 10 hospitals in Budapest, Hungary. Subjects were enrolled in eight hospitals in Sweden until April 1997. The cases included all patients who developed anaphylaxis while in hospital for other reasons. The diagnoses were confirmed by a review committee of physicians without knowledge of precipitating exposures. Controls were a random sample of other patients in the participating hospitals. Information on exposures in the 48 hours preceding the reaction and on relevant medical history and demographic factors was obtained by interview and from hospital records. Incidence rates were estimated to allow the calculation of absolute risks. There were 184 cases and 1003 controls included in the final dataset.

In addition to the main study, some 80 cases of anaphylaxis developing in the ambulatory population and resulting in admission to hospital and 345 matched hospital controls were enrolled during the pilot phase.

Results

The incidence of anaphylaxis among hospital patients exposed to various drugs and radiographic contrast media was estimated to range from 5-378 cases per 100,000 exposed. At the low end were most analgesics and antibiotics; the incidence was intermediate for blood, dextran, pentoxifylline and contrast media; it was highest for streptokinase, plasma, and anti-snake venom.