Definition, Epidemiology, and Pathogenesis

Abstract

Anaphylaxis is a severe reaction that is rapid in onset and may lead to death. The prevalence of anaphylaxis seems to be increasing. However, knowledge about the epidemiology of anaphylaxis is based on data from various sources: clinical practice, large secondary clinical and administrative databases of primary care or hospitalized patients, and recent surveys with representative samples of the general population. The different inclusion criteria, settings, geographic area, and time at which these studies are performed may explain the huge difference in prevalence, incidence, and triggers. Nevertheless, it is clear that the incidence and prevalence of anaphylaxis are higher than previously thought. Publications from the last 5 years reveal an incidence of between 12.8 and 112 episodes per 100,000 person-years. Furthermore, depending on the trigger of anaphylaxis, the symptoms of the reaction could differ enormously, the mechanism initiating the anaphylactic reaction, and the effector cells involved; therefore, the biomarkers may differ according to these factors. However, many of these data are missing in epidemiologic studies. Thus, in order to increase the knowledge of anaphylaxis, there is a need to improve epidemiologic research standardizing information provided, as summarized in this review.